Guest ship Posted July 26, 2007 Posted July 26, 2007 Hi Is it true that WindowsXP Pro has a 3GB limit on addressable RAM space? We have a user who regularly uses spreadsheets of 1.5 to 2+GB in size (on the hard disk). - How much RAM should we give her? - i.e. Is there any point in giving her over 3GB ? Ship Shiperton Henethe2
Guest Mark L. Ferguson Posted July 26, 2007 Posted July 26, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? There is a limit on each running Process (4 gigs). With two Processors, I suppose 8 gigs would have a point. Take a look at this site. Virtual Memory in Windows XP: http://aumha.org/win5/a/xpvm.php -- Mark L. Ferguson e-mail subject line must include "QZ" or it's deleted .. "ship" <shiphen@gmail.com> wrote in message news:1185467208.883054.107940@g4g2000hsf.googlegroups.com... > Hi > > Is it true that WindowsXP Pro has a 3GB limit on addressable RAM > space? > > We have a user who regularly uses spreadsheets of 1.5 to 2+GB in size > (on the hard disk). > - How much RAM should we give her? > - i.e. Is there any point in giving her over 3GB ? > > > Ship > > Shiperton Henethe2 >
Guest Curt Christianson Posted July 26, 2007 Posted July 26, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? Hi Ship, In addition to Mark's advice, you may want to read this article by MVP Tim Slattery: 4 GB RAM in Windows XP http://members.cox.net/slatteryt/RAM.html -- HTH, Curt Windows Support Center http://www.aumha.org Practically Nerded,... http://dundats.mvps.org/Index.htm "ship" <shiphen@gmail.com> wrote in message news:1185467208.883054.107940@g4g2000hsf.googlegroups.com... | Hi | | Is it true that WindowsXP Pro has a 3GB limit on addressable RAM | space? | | We have a user who regularly uses spreadsheets of 1.5 to 2+GB in size | (on the hard disk). | - How much RAM should we give her? | - i.e. Is there any point in giving her over 3GB ? | | | Ship | | Shiperton Henethe2 |
Guest John John Posted July 26, 2007 Posted July 26, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? Windows XP 32-bit has an addressable limit of 4GB RAM. Put a full 4GB of RAM in the machine if it supports it. You will not be able to use the full 4GB because some of the RAM at the Top of Memory address range must be made available to other hardware. What you will be able to use depends on what the other hardware needs, don't expect any more than 3.5 GB, it could be anything between 2.75 to 3.5GB. The 4GB RAM address limit applies to multi-processor machines also. If the application is "LARGEADDRESSWARE" aware then you may be able to use 4GB tuning by using the /3GB switch in the boot.ini file. That will not allow Windows to increase the addressable memory range but it will limit the operating system to 1GB of memory and allow LARGEADDRESSWARE applications to use 3GB. John ship wrote: > Hi > > Is it true that WindowsXP Pro has a 3GB limit on addressable RAM > space? > > We have a user who regularly uses spreadsheets of 1.5 to 2+GB in size > (on the hard disk). > - How much RAM should we give her? > - i.e. Is there any point in giving her over 3GB ? > > > Ship > > Shiperton Henethe2 >
Guest Jim Posted July 26, 2007 Posted July 26, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? "ship" <shiphen@gmail.com> wrote in message news:1185467208.883054.107940@g4g2000hsf.googlegroups.com... > Hi > > Is it true that WindowsXP Pro has a 3GB limit on addressable RAM > space? > > We have a user who regularly uses spreadsheets of 1.5 to 2+GB in size > (on the hard disk). > - How much RAM should we give her? > - i.e. Is there any point in giving her over 3GB ? > > > Ship > > Shiperton Henethe2 > The amount of physical RAM cannot exceed 4 GB since Windows XP does not employ the PAE facility (a CPU instruction, etc.). However, when Windows loads, it reserves some of this physical RAM for its own uses. Users report that the remainder is somewhat more than 3 GB. The amount of virtual address space cannot exceet 4 GB. However, since Windows must be mapped into the virtual address space of all processes, the amount that is available to user programs and data is usually 2 GB. You can increase the amount of virtual address space to 3 GB with the well documented /3GB switch. Have you implemented the /3GB switch? Thus, my answer is there is a slight benefit to more than 3 GB. However, unless the particular computer is showing some kind of performance degradation, then I see little reason for action. It would be useful to study the memory usage of the program while the user is doing something with the files. In addition, if you have not implemented the use of the /3GB switch, and if the programs run without problems, then the computer does not need more than 2GB of physical RAM. Jim
Guest Ken Blake, MVP Posted July 26, 2007 Posted July 26, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? On Thu, 26 Jul 2007 16:26:48 -0000, ship <shiphen@gmail.com> wrote: > Hi > > Is it true that WindowsXP Pro has a 3GB limit on addressable RAM > space? No, it's 4GB. However in 32-bit Windows XP (and Vista too) some of that address space is used for hardware devices and can not be used by applications or Windows itself. Exactly how much that is depends on what hardware is installed, but most machines can use a maximum of somewhere around 3.1GB of RAM. > We have a user who regularly uses spreadsheets of 1.5 to 2+GB in size > (on the hard disk). > - How much RAM should we give her? 2.5-3GB sounds like it should suffice. > - i.e. Is there any point in giving her over 3GB ? No. -- Ken Blake, Microsoft MVP Windows - Shell/User Please Reply to the Newsgroup
Guest Tim Slattery Posted July 26, 2007 Posted July 26, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? John John <audetweld@nbnet.nb.ca> wrote: >If the application is "LARGEADDRESSWARE" aware then you may be able to >use 4GB tuning by using the /3GB switch in the boot.ini file. That will >not allow Windows to increase the addressable memory range but it will >limit the operating system to 1GB of memory and allow LARGEADDRESSWARE >applications to use 3GB. But be aware that this applies to the 4GB Virtual Address space given to each process running with XP, NOT to physical RAM. -- Tim Slattery MS MVP(DTS) Slattery_T@bls.gov http://members.cox.net/slatteryt
Guest HEMI-Powered Posted July 26, 2007 Posted July 26, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? Curt Christianson added these comments in the current discussion du jour ... > Hi Ship, > > In addition to Mark's advice, you may want to read this > article by MVP Tim Slattery: > > 4 GB RAM in Windows XP > http://members.cox.net/slatteryt/RAM.html > It has been explained to me before, but I still do not understand it. I have 4 gig but when I look at Taskmanager, it shows only 3. I use the term "Windows hijacks one gig" to describe this. That's not meant to be technical, just what it looks like. There is a logical explanation, but AFAIK, the real memory space maximum for a single CPU that any XP apps can access is 3 gig. -- HP, aka Jerry
Guest HEMI-Powered Posted July 26, 2007 Posted July 26, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? Jim added these comments in the current discussion du jour ... > > "ship" <shiphen@gmail.com> wrote in message > news:1185467208.883054.107940@g4g2000hsf.googlegroups.com... >> Hi >> >> Is it true that WindowsXP Pro has a 3GB limit on addressable >> RAM space? >> >> We have a user who regularly uses spreadsheets of 1.5 to 2+GB >> in size (on the hard disk). >> - How much RAM should we give her? >> - i.e. Is there any point in giving her over 3GB ? >> >> >> Ship >> >> Shiperton Henethe2 >> > The amount of physical RAM cannot exceed 4 GB since Windows XP > does not employ the PAE facility (a CPU instruction, etc.). > However, when Windows loads, it reserves some of this physical > RAM for its own uses. Users report that the remainder is > somewhat more than 3 GB. According to Taskmanager on my 4 gig AMD system, I have 3,144,112 = 2.9985 GB, essentially 3, so Windows apparently takes 1 of my gigs for "its own uses", whatever that is. > The amount of virtual address space cannot exceet 4 GB. > However, since Windows must be mapped into the virtual address > space of all processes, the amount that is available to user > programs and data is usually 2 GB. You can increase the > amount of virtual address space to 3 GB with the well > documented /3GB switch. Have you implemented the /3GB switch? Never heard of this. Is there a /4GB switch so I can take advantage of a gig I paid $200+ for but cannot access? When I discoverd that, I felt cheated, but then, if I'd only bought 3 gig, then I'd have only 2, right? > Thus, my answer is there is a slight benefit to more than 3 > GB. However, unless the particular computer is showing some > kind of performance degradation, > then I see little reason for action. It would be useful to > study the memory usage of the program while the user is doing > something with the files. In addition, if you have not > implemented the use of the /3GB switch, and if the programs > run without problems, then the computer does not need more > than 2GB of physical RAM. > -- HP, aka Jerry
Guest Ken Blake, MVP Posted July 26, 2007 Posted July 26, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? On Thu, 26 Jul 2007 21:18:19 GMT, "HEMI-Powered" <none@none.en> wrote: > Jim added these comments in the current discussion du jour ... > > > > > "ship" <shiphen@gmail.com> wrote in message > > news:1185467208.883054.107940@g4g2000hsf.googlegroups.com... > >> Hi > >> > >> Is it true that WindowsXP Pro has a 3GB limit on addressable > >> RAM space? > >> > >> We have a user who regularly uses spreadsheets of 1.5 to 2+GB > >> in size (on the hard disk). > >> - How much RAM should we give her? > >> - i.e. Is there any point in giving her over 3GB ? > >> > >> > >> Ship > >> > >> Shiperton Henethe2 > >> > > The amount of physical RAM cannot exceed 4 GB since Windows XP > > does not employ the PAE facility (a CPU instruction, etc.). > > However, when Windows loads, it reserves some of this physical > > RAM for its own uses. Users report that the remainder is > > somewhat more than 3 GB. > > According to Taskmanager on my 4 gig AMD system, I have 3,144,112 > = 2.9985 GB, essentially 3, so Windows apparently takes 1 of my > gigs for "its own uses", whatever that is. > > > The amount of virtual address space cannot exceet 4 GB. > > However, since Windows must be mapped into the virtual address > > space of all processes, the amount that is available to user > > programs and data is usually 2 GB. You can increase the > > amount of virtual address space to 3 GB with the well > > documented /3GB switch. Have you implemented the /3GB switch? > > Never heard of this. Is there a /4GB switch so I can take > advantage of a gig I paid $200+ for but cannot access? When I > discoverd that, I felt cheated, but then, if I'd only bought 3 > gig, then I'd have only 2, right? No, wrong. All 32-bit machines have that same 4GB address space. It takes that amount of address space (not RAM)--usually a little less than 1GB--from the 4GB total, leaving around 3.1GB of address for real memory. If you had 2GB of RAM, it would fit into the remaining 3.1GB without a problem. -- Ken Blake, Microsoft MVP Windows - Shell/User Please Reply to the Newsgroup
Guest Jim Posted July 26, 2007 Posted July 26, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? "HEMI-Powered" <none@none.en> wrote in message news:Xns9979B014456F0ReplyScoreID@140.99.99.130... > Jim added these comments in the current discussion du jour ... > >> >> "ship" <shiphen@gmail.com> wrote in message >> news:1185467208.883054.107940@g4g2000hsf.googlegroups.com... >>> Hi >>> >>> Is it true that WindowsXP Pro has a 3GB limit on addressable >>> RAM space? >>> >>> We have a user who regularly uses spreadsheets of 1.5 to 2+GB >>> in size (on the hard disk). >>> - How much RAM should we give her? >>> - i.e. Is there any point in giving her over 3GB ? >>> >>> >>> Ship >>> >>> Shiperton Henethe2 >>> >> The amount of physical RAM cannot exceed 4 GB since Windows XP >> does not employ the PAE facility (a CPU instruction, etc.). >> However, when Windows loads, it reserves some of this physical >> RAM for its own uses. Users report that the remainder is >> somewhat more than 3 GB. > > According to Taskmanager on my 4 gig AMD system, I have 3,144,112 > = 2.9985 GB, essentially 3, so Windows apparently takes 1 of my > gigs for "its own uses", whatever that is. > >> The amount of virtual address space cannot exceet 4 GB. >> However, since Windows must be mapped into the virtual address >> space of all processes, the amount that is available to user >> programs and data is usually 2 GB. You can increase the >> amount of virtual address space to 3 GB with the well >> documented /3GB switch. Have you implemented the /3GB switch? > > Never heard of this. Is there a /4GB switch so I can take > advantage of a gig I paid $200+ for but cannot access? When I > discoverd that, I felt cheated, but then, if I'd only bought 3 > gig, then I'd have only 2, right? There is no /4GB switch. There never will be one on a 32 bit operating system. The answer to you second question is probably. It all depends on how XP manages the physical memory. The /3GB switch controls the size of the user portion of the virtual address space (which is not the same as RAM). The operating system must be mapped into your virtual address space if: 1. You expect see output on the screen 2. You expect to send data to the operating system from the keyboard 3. You like to use a mouse 4. You want to read from mass storage or to write to it. 5. You want to access the internet 6. You want to send output to your printer 7. You want to use your scanner. Now, if you don't want to do any of those things, you don't need a computer. Jim
Guest John John Posted July 27, 2007 Posted July 27, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? Tim Slattery wrote: > John John <audetweld@nbnet.nb.ca> wrote: > > >>If the application is "LARGEADDRESSWARE" aware then you may be able to >>use 4GB tuning by using the /3GB switch in the boot.ini file. That will >>not allow Windows to increase the addressable memory range but it will >>limit the operating system to 1GB of memory and allow LARGEADDRESSWARE >>applications to use 3GB. > > > But be aware that this applies to the 4GB Virtual Address space given > to each process running with XP, NOT to physical RAM. "Typically, a process running under Windows 2000 or Windows Server 2003 can access up to 2 GB of memory address space (assuming the /3GB switch was not used) with some of the memory being physical memory and some being virtual memory. The more programs (and, therefore, more processes) that run, the more memory you commit up to the full 2 GB of address space. When this situation occurs, the paging process increases dramatically and performance may be negatively impacted... A program that requests 3 GB of memory is more likely to be able to have more of its memory remain in physical memory rather than be paged out. This increases the performance of programs that are capable of using the /3GB switch. The exception is when the /3GB switch is used in conjunction with... [end quote] Large memory support is available in Windows Server 2003 and in Windows 2000 http://support.microsoft.com/kb/283037/ Windows XP is not PAE capable. John
Guest HEMI-Powered Posted July 27, 2007 Posted July 27, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? Ken Blake, MVP added these comments in the current discussion du jour ... >> Never heard of this. Is there a /4GB switch so I can take >> advantage of a gig I paid $200+ for but cannot access? When I >> discoverd that, I felt cheated, but then, if I'd only bought >> 3 gig, then I'd have only 2, right? > > No, wrong. All 32-bit machines have that same 4GB address > space. It takes that amount of address space (not > RAM)--usually a little less than 1GB--from the 4GB total, > leaving around 3.1GB of address for real memory. If you had > 2GB of RAM, it would fit into the remaining 3.1GB without a > problem. So, then the real limit is 3 gig of USABLE RAM, so if I had bought only 3 gig instead of 4, what would taskmanager show, 3.1GB or 2.1GB? Sorry, I understand clearly the difference between usable RAM and address space, which is simply defined by the bit length, but I still do not understand how much RAM would be usable to me had I bought less than 4. If you could clarify it simply, I would appreciate knowing. Thank you. -- HP, aka Jerry
Guest HEMI-Powered Posted July 27, 2007 Posted July 27, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? Jim added these comments in the current discussion du jour ... >> Never heard of this. Is there a /4GB switch so I can take >> advantage of a gig I paid $200+ for but cannot access? When I >> discoverd that, I felt cheated, but then, if I'd only bought >> 3 gig, then I'd have only 2, right? > There is no /4GB switch. There never will be one on a 32 bit > operating system. > The answer to you second question is probably. It all depends > on how XP manages the physical memory. > The /3GB switch controls the size of the user portion of the > virtual address space (which is not the same as > RAM). > The operating system must be mapped into your virtual address > space if: 1. You expect see output on the screen > 2. You expect to send data to the operating system from the > keyboard 3. You like to use a mouse > 4. You want to read from mass storage or to write to it. > 5. You want to access the internet > 6. You want to send output to your printer > 7. You want to use your scanner. > Now, if you don't want to do any of those things, you don't > need a computer. Jim Thank you, Jim. Here is my main and ONLY interest: I want my applications, primarily graphics apps such as my scanner and graphics editor, to run as quickly as possible by giving them the most possible room in usable RAM, at the same time as a dozen other things are sitting in memory but basically unused. In my case, I've got 3 instances of Windows Explorer on my task bar, IE6, OE6, Excel, Word, Taskmanager itself, the Recycle Bin, a couple of NNTP news readers/posters such as Xnews that I'm using to compose this reply, PSP 9, XP's Search function, a graphics thumbnail database, and a couple of Notepad files. NONE of those things are ever doing anything at all, or nothing that is even a minor user of memory, when I am doing complicated raster graphics work in PSP, yet it is slower than I would expect with a 2.6 gig AMD Athlon CPU and all that 4 gig/3 gig usable RAM. My particular set of running programs isn't the issue nor is it whether or not PSP 9 is a efficient program or not, I simply have been curious since I had this PC custom built a couple years ago why PSP 9 failed to run more than about 25-40% faster than it did on a 1.6 gig AMD machine with XP SP1 and only 512 MB of memory. If the answer is "get another graphics editor", I will thank but say "no thanks, not right now". But, if I have my system set up sub-optimally out of ignorance - and my computer guru and builder nephew of mine is equally ignorant - then I would appreciate just a heads-up and I will investigate the details on my own. In short, I would ask you to please not lecture me on my stupidity for wanting to do what I am doing and please not suggest I buy a new PC with Vista, but to politely point me in a direction that I can help myself. Thank you. -- HP, aka Jerry
Guest Bob I Posted July 27, 2007 Posted July 27, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? IF, you had installed 3GB AND your video card/graphic subsystem does NOT use main RAM you would have 3 GB, the 4th GB of RAM has some portion of it's address space PREempted by hardware addresses. The area preempted is related to the hardware installed, less hardware, fewer address required to be assigned, less RAM goes "missing". Add more hardware, more addresses get used, less RAM addressable. IF you went really nuts with the add-in cards and video memory assignments you could certainly clobber RAM adressing back to under 3 GB available. HEMI-Powered wrote: > Ken Blake, MVP added these comments in the current discussion du > jour ... > > >>>Never heard of this. Is there a /4GB switch so I can take >>>advantage of a gig I paid $200+ for but cannot access? When I >>>discoverd that, I felt cheated, but then, if I'd only bought >>>3 gig, then I'd have only 2, right? >> >>No, wrong. All 32-bit machines have that same 4GB address >>space. It takes that amount of address space (not >>RAM)--usually a little less than 1GB--from the 4GB total, >>leaving around 3.1GB of address for real memory. If you had >>2GB of RAM, it would fit into the remaining 3.1GB without a >>problem. > > > So, then the real limit is 3 gig of USABLE RAM, so if I had bought > only 3 gig instead of 4, what would taskmanager show, 3.1GB or > 2.1GB? Sorry, I understand clearly the difference between usable > RAM and address space, which is simply defined by the bit length, > but I still do not understand how much RAM would be usable to me > had I bought less than 4. If you could clarify it simply, I would > appreciate knowing. Thank you. >
Guest Ken Blake, MVP Posted July 27, 2007 Posted July 27, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? On Fri, 27 Jul 2007 15:30:08 GMT, "HEMI-Powered" <none@none.en> wrote: > Ken Blake, MVP added these comments in the current discussion du > jour ... > > >> Never heard of this. Is there a /4GB switch so I can take > >> advantage of a gig I paid $200+ for but cannot access? When I > >> discoverd that, I felt cheated, but then, if I'd only bought > >> 3 gig, then I'd have only 2, right? > > > > No, wrong. All 32-bit machines have that same 4GB address > > space. It takes that amount of address space (not > > RAM)--usually a little less than 1GB--from the 4GB total, > > leaving around 3.1GB of address for real memory. If you had > > 2GB of RAM, it would fit into the remaining 3.1GB without a > > problem. > > So, then the real limit is 3 gig of USABLE RAM, Yes. Actually usually a little more. > so if I had bought > only 3 gig instead of 4, what would taskmanager show, 3.1GB or > 2.1GB? Neither. If you had 3GB, it would show 3GB. > Sorry, I understand clearly the difference between usable > RAM and address space, which is simply defined by the bit length, > but I still do not understand how much RAM would be usable to me > had I bought less than 4. If you could clarify it simply, I would > appreciate knowing. Thank you. *All* the RAM you have is usable to you, up to a maximum of *around* 3.1GB (again, depending on your hardware). Anything more than that is not usable. This 3.1GB or so limit is on 32-bit Windows. If you were running 64-bit Windows, it would go away. -- Ken Blake, Microsoft MVP Windows - Shell/User Please Reply to the Newsgroup
Guest Swifty Posted July 27, 2007 Posted July 27, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? > - How much RAM should we give her? > - i.e. Is there any point in giving her over 3GB ? Some PC manufacturers fit a hardware memory management module that is restricted to 3Gb - some Lenovo ThinkPads and certainly my 8212 desktop are affected. No matter how much RAM you install, you cannot access more than 3Gb of it if you have one of these. I would imagine that other manufacturers have similarly affected systems. -- Steve Swift http://www.swiftys.org.uk/swifty.html http://www.ringers.org.uk
Guest HEMI-Powered Posted July 27, 2007 Posted July 27, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? Bob I added these comments in the current discussion du jour ... > IF, you had installed 3GB AND your video card/graphic > subsystem does NOT use main RAM you would have 3 GB, the 4th > GB of RAM has some portion of it's address space PREempted by > hardware addresses. The area preempted is related to the > hardware installed, less hardware, fewer address required to > be assigned, less RAM goes "missing". Add more hardware, more > addresses get used, less RAM addressable. IF you went really > nuts with the add-in cards and video memory assignments you > could certainly clobber RAM adressing back to under 3 GB > available. Thank you. AFAIK, my ATI Radeon does not use main RAM. I don't remember the fine details, but I think it is maxed out at 256MB. I had my current PC maxed out on everything except the absolute fastest clock speed AMD chip. I didn't do that because the 3X price ding only would've produced a modest performance increase by my estimates. > HEMI-Powered wrote: > >> Ken Blake, MVP added these comments in the current discussion >> du jour ... >> >> >>>>Never heard of this. Is there a /4GB switch so I can take >>>>advantage of a gig I paid $200+ for but cannot access? When >>>>I discoverd that, I felt cheated, but then, if I'd only >>>>bought 3 gig, then I'd have only 2, right? >>> >>>No, wrong. All 32-bit machines have that same 4GB address >>>space. It takes that amount of address space (not >>>RAM)--usually a little less than 1GB--from the 4GB total, >>>leaving around 3.1GB of address for real memory. If you had >>>2GB of RAM, it would fit into the remaining 3.1GB without a >>>problem. >> >> >> So, then the real limit is 3 gig of USABLE RAM, so if I had >> bought only 3 gig instead of 4, what would taskmanager show, >> 3.1GB or 2.1GB? Sorry, I understand clearly the difference >> between usable RAM and address space, which is simply defined >> by the bit length, but I still do not understand how much >> RAM would be usable to me had I bought less than 4. If you >> could clarify it simply, I would appreciate knowing. Thank >> you. >> > > -- HP, aka Jerry
Guest Ken Blake, MVP Posted July 27, 2007 Posted July 27, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? On Fri, 27 Jul 2007 20:12:52 +0100, Swifty <Steve.J.Swift@gmail.com> wrote: > > - How much RAM should we give her? > > - i.e. Is there any point in giving her over 3GB ? > > Some PC manufacturers fit a hardware memory management module that is > restricted to 3Gb - some Lenovo ThinkPads and certainly my 8212 desktop > are affected. No matter how much RAM you install, you cannot access more > than 3Gb of it if you have one of these. It's true that you can't access more than about 3.1GB on any 32-bit Windows system. But that's *not* the reason. 32-bit XP can use up to 4GB of address space. However the 4GB address space has to be shared with memory used for other devices. So Windows (not just XP but all 32-bit versions, including 32-bit Vista) can't use that entire 4GB for itself. How much it can use is around 3GB, but depends on what devices are installed. It's normally a little more than 3GB. -- Ken Blake, Microsoft MVP Windows - Shell/User Please Reply to the Newsgroup
Guest HEMI-Powered Posted July 27, 2007 Posted July 27, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? Ken Blake, MVP added these comments in the current discussion du jour ... >> So, then the real limit is 3 gig of USABLE RAM, > > Yes. Actually usually a little more. Are you using 1,000 or 1,024 bytes/KB? If the former, than I show 3.14GB. If the latter, I show about 2.98GB. "Three" seems like such a nice round number, I just use that. > >> so if I had bought >> only 3 gig instead of 4, what would taskmanager show, 3.1GB >> or 2.1GB? > > Neither. If you had 3GB, it would show 3GB. So, I wasted over $200 on that 4th gig of RAM I installed? I'm not disputing you, I am just shaking my head from lack of understanding. Let me try this: IF, big "if", a program could be written to get at the upper gig somehow, then, yes, I would have the entire $850 worth of memory I paid for. But, since standard 32-bit XP cannot, I "lose" it effectly. Is /that/ correct? > >> Sorry, I understand clearly the difference between usable >> RAM and address space, which is simply defined by the bit >> length, but I still do not understand how much RAM would be >> usable to me had I bought less than 4. If you could clarify >> it simply, I would appreciate knowing. Thank you. > > *All* the RAM you have is usable to you, up to a maximum of > *around* 3.1GB (again, depending on your hardware). Anything > more than that is not usable. See above for clarification on 3.14 gig. > This 3.1GB or so limit is on 32-bit Windows. If you were > running 64-bit Windows, it would go away. I didn't buy 64-bit XP even though it was available because my assessment, rightly or wrongly, was that it was extremely buggy, unstable, lacking in drivers to really take advantage of the increased address space, AND most importantly, none of my older apps would be able to use it anyway. Is this right or wrong? Thanks for you comments. -- HP, aka Jerry
Guest Ken Blake, MVP Posted July 27, 2007 Posted July 27, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? On Fri, 27 Jul 2007 20:31:41 GMT, "HEMI-Powered" <none@none.en> wrote: > Ken Blake, MVP added these comments in the current discussion du > jour ... > > >> So, then the real limit is 3 gig of USABLE RAM, > > > > Yes. Actually usually a little more. > > Are you using 1,000 or 1,024 bytes/KB? If the former, than I show > 3.14GB. If the latter, I show about 2.98GB. "Three" seems like > such a nice round number, I just use that. "Three" is close enough, especially since it varies for different computers. > >> so if I had bought > >> only 3 gig instead of 4, what would taskmanager show, 3.1GB > >> or 2.1GB? > > > > Neither. If you had 3GB, it would show 3GB. > > So, I wasted over $200 on that 4th gig of RAM I installed? I'm afraid so. > I'm > not disputing you, I am just shaking my head from lack of > understanding. Let me try this: IF, big "if", a program could be > written to get at the upper gig somehow, then, yes, I would have > the entire $850 worth of memory I paid for. But, since standard > 32-bit XP cannot, I "lose" it effectly. Is /that/ correct? Yes. > >> Sorry, I understand clearly the difference between usable > >> RAM and address space, which is simply defined by the bit > >> length, but I still do not understand how much RAM would be > >> usable to me had I bought less than 4. If you could clarify > >> it simply, I would appreciate knowing. Thank you. > > > > *All* the RAM you have is usable to you, up to a maximum of > > *around* 3.1GB (again, depending on your hardware). Anything > > more than that is not usable. > > See above for clarification on 3.14 gig. > > > This 3.1GB or so limit is on 32-bit Windows. If you were > > running 64-bit Windows, it would go away. > > I didn't buy 64-bit XP even though it was available because my > assessment, rightly or wrongly, was that it was extremely buggy, I have no experience with it personally, but I haven't heard that. > unstable, Same thing. I haven't heard that either. I know a few people running it, all without problems. > lacking in drivers to really take advantage of the > increased address space, Drivers are often lacking, and that's the big issue with both 64-bit XP and 64-bit Vista. But the drivers issue isn't that you won't "really [be able to] take advantage of the increased address space," but rather that if the drivers aren't available for a particular piece of hardware, you can't use that hardware. 64-bit Windows (whether XP or Vista) is new enough that you may not be able to get drivers for all your hardware. > AND most importantly, none of my older > apps would be able to use it anyway. Is this right or wrong? Well, I'm not sure what you mean by that. Your apps older will be able to use 64-bit Windows, but 32-bit apps with a 64-bit operating system will not give you any improvement in performance. For 64-bit Windows to improve things, you need 64-bit apps, and there are very few of those available yet. However if the apps you use can make effective use of more than that 3GB of RAM, and you have that much RAM, then even 32-bit apps can show improvement by using the extra memory. For most people, it would be rare though, that they could make effective use of over 3GB. -- Ken Blake, Microsoft MVP Windows - Shell/User Please Reply to the Newsgroup
Guest HEMI-Powered Posted July 28, 2007 Posted July 28, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? Ken Blake, MVP added these comments in the current discussion du jour ... Dang! Wish I'd have talked to you first! I'd be over $200 richer. Sigh! Thanks, Ken. > On Fri, 27 Jul 2007 20:31:41 GMT, "HEMI-Powered" > <none@none.en> wrote: > >> Ken Blake, MVP added these comments in the current discussion >> du jour ... >> >> >> So, then the real limit is 3 gig of USABLE RAM, >> > >> > Yes. Actually usually a little more. >> >> Are you using 1,000 or 1,024 bytes/KB? If the former, than I >> show 3.14GB. If the latter, I show about 2.98GB. "Three" >> seems like such a nice round number, I just use that. > > > "Three" is close enough, especially since it varies for > different computers. > > > >> >> so if I had bought >> >> only 3 gig instead of 4, what would taskmanager show, >> >> 3.1GB or 2.1GB? >> > >> > Neither. If you had 3GB, it would show 3GB. >> >> So, I wasted over $200 on that 4th gig of RAM I installed? > > > I'm afraid so. > > >> I'm >> not disputing you, I am just shaking my head from lack of >> understanding. Let me try this: IF, big "if", a program could >> be written to get at the upper gig somehow, then, yes, I >> would have the entire $850 worth of memory I paid for. But, >> since standard 32-bit XP cannot, I "lose" it effectly. Is >> /that/ correct? > > > Yes. > > >> >> Sorry, I understand clearly the difference between usable >> >> RAM and address space, which is simply defined by the bit >> >> length, but I still do not understand how much RAM would >> >> be usable to me had I bought less than 4. If you could >> >> clarify it simply, I would appreciate knowing. Thank you. >> > >> > *All* the RAM you have is usable to you, up to a maximum of >> > *around* 3.1GB (again, depending on your hardware). >> > Anything more than that is not usable. >> >> See above for clarification on 3.14 gig. >> >> > This 3.1GB or so limit is on 32-bit Windows. If you were >> > running 64-bit Windows, it would go away. >> >> I didn't buy 64-bit XP even though it was available because >> my assessment, rightly or wrongly, was that it was extremely >> buggy, > > > I have no experience with it personally, but I haven't heard > that. > > >> unstable, > > > Same thing. I haven't heard that either. I know a few people > running it, all without problems. > > >> lacking in drivers to really take advantage of the increased >> address space, > > > > Drivers are often lacking, and that's the big issue with both > 64-bit XP and 64-bit Vista. But the drivers issue isn't that > you won't "really [be able to] take advantage of the increased > address space," but rather that if the drivers aren't > available for a particular piece of hardware, you can't use > that hardware. 64-bit Windows (whether XP or Vista) is new > enough that you may not be able to get drivers for all your > hardware. > > >> AND most importantly, none of my older apps would be able to >> use it anyway. Is this right or wrong? > > > > Well, I'm not sure what you mean by that. Your apps older will > be able to use 64-bit Windows, but 32-bit apps with a 64-bit > operating system will not give you any improvement in > performance. For 64-bit Windows to improve things, you need > 64-bit apps, and there are very few of those available yet. > > However if the apps you use can make effective use of more > than that 3GB of RAM, and you have that much RAM, then even > 32-bit apps can show improvement by using the extra memory. > For most people, it would be rare though, that they could make > effective use of over 3GB. > -- HP, aka Jerry
Guest Ken Blake, MVP Posted July 28, 2007 Posted July 28, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? On Sat, 28 Jul 2007 00:13:41 GMT, "HEMI-Powered" <none@none.en> wrote: > Ken Blake, MVP added these comments in the current discussion du > jour ... > > Dang! Wish I'd have talked to you first! I'd be over $200 richer. > Sigh! Thanks, Ken. You're welcome. Sorry you didn't check first. > > > On Fri, 27 Jul 2007 20:31:41 GMT, "HEMI-Powered" > > <none@none.en> wrote: > > > >> Ken Blake, MVP added these comments in the current discussion > >> du jour ... > >> > >> >> So, then the real limit is 3 gig of USABLE RAM, > >> > > >> > Yes. Actually usually a little more. > >> > >> Are you using 1,000 or 1,024 bytes/KB? If the former, than I > >> show 3.14GB. If the latter, I show about 2.98GB. "Three" > >> seems like such a nice round number, I just use that. > > > > > > "Three" is close enough, especially since it varies for > > different computers. > > > > > > > >> >> so if I had bought > >> >> only 3 gig instead of 4, what would taskmanager show, > >> >> 3.1GB or 2.1GB? > >> > > >> > Neither. If you had 3GB, it would show 3GB. > >> > >> So, I wasted over $200 on that 4th gig of RAM I installed? > > > > > > I'm afraid so. > > > > > >> I'm > >> not disputing you, I am just shaking my head from lack of > >> understanding. Let me try this: IF, big "if", a program could > >> be written to get at the upper gig somehow, then, yes, I > >> would have the entire $850 worth of memory I paid for. But, > >> since standard 32-bit XP cannot, I "lose" it effectly. Is > >> /that/ correct? > > > > > > Yes. > > > > > >> >> Sorry, I understand clearly the difference between usable > >> >> RAM and address space, which is simply defined by the bit > >> >> length, but I still do not understand how much RAM would > >> >> be usable to me had I bought less than 4. If you could > >> >> clarify it simply, I would appreciate knowing. Thank you. > >> > > >> > *All* the RAM you have is usable to you, up to a maximum of > >> > *around* 3.1GB (again, depending on your hardware). > >> > Anything more than that is not usable. > >> > >> See above for clarification on 3.14 gig. > >> > >> > This 3.1GB or so limit is on 32-bit Windows. If you were > >> > running 64-bit Windows, it would go away. > >> > >> I didn't buy 64-bit XP even though it was available because > >> my assessment, rightly or wrongly, was that it was extremely > >> buggy, > > > > > > I have no experience with it personally, but I haven't heard > > that. > > > > > >> unstable, > > > > > > Same thing. I haven't heard that either. I know a few people > > running it, all without problems. > > > > > >> lacking in drivers to really take advantage of the increased > >> address space, > > > > > > > > Drivers are often lacking, and that's the big issue with both > > 64-bit XP and 64-bit Vista. But the drivers issue isn't that > > you won't "really [be able to] take advantage of the increased > > address space," but rather that if the drivers aren't > > available for a particular piece of hardware, you can't use > > that hardware. 64-bit Windows (whether XP or Vista) is new > > enough that you may not be able to get drivers for all your > > hardware. > > > > > >> AND most importantly, none of my older apps would be able to > >> use it anyway. Is this right or wrong? > > > > > > > > Well, I'm not sure what you mean by that. Your apps older will > > be able to use 64-bit Windows, but 32-bit apps with a 64-bit > > operating system will not give you any improvement in > > performance. For 64-bit Windows to improve things, you need > > 64-bit apps, and there are very few of those available yet. > > > > However if the apps you use can make effective use of more > > than that 3GB of RAM, and you have that much RAM, then even > > 32-bit apps can show improvement by using the extra memory. > > For most people, it would be rare though, that they could make > > effective use of over 3GB. > > > > > > -- > HP, aka Jerry -- Ken Blake, Microsoft MVP Windows - Shell/User Please Reply to the Newsgroup
Guest Swifty Posted July 28, 2007 Posted July 28, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? > How much it can use is around 3GB, but depends on what devices are > installed. It's normally a little more than 3GB. I'm not sure if we're agreeing or disagreeing :-) Just in case the OP has an affected Lenovo system (or one with comparable hardware from another supplier, the memory module is an industry standard one): There is absolutely no difference in these cases between a system with 3Gb installed memory and 4Gb installed memory. Except in your bank balance and the amount of energy you waste. The memory management hardware does not allow the top two address bits to be 11, so there is no way for it to reach real memory above 3Gb. This has nothing to do with Windows; it is a hardware limitation affecting Linux as well, or anything else you care to boot. I work for IBM, and this discussion has been raging for months inside IBM. The bottom line is that you have to check the hardware specifications of the system concerned to see if it supports more than 3Gb or real memory. These are sometime worded rather obscurely. -- Steve Swift http://www.swiftys.org.uk/swifty.html http://www.ringers.org.uk
Guest John John Posted July 28, 2007 Posted July 28, 2007 Re: Does Windows XP Pro have a 3GB limit on RAM ? Swifty wrote: >> How much it can use is around 3GB, but depends on what devices are >> installed. It's normally a little more than 3GB. > > > I'm not sure if we're agreeing or disagreeing :-) > > Just in case the OP has an affected Lenovo system (or one with > comparable hardware from another supplier, the memory module is an > industry standard one): > > There is absolutely no difference in these cases between a system with > 3Gb installed memory and 4Gb installed memory. Except in your bank > balance and the amount of energy you waste. The memory management > hardware does not allow the top two address bits to be 11, so there is > no way for it to reach real memory above 3Gb. > > This has nothing to do with Windows; it is a hardware limitation > affecting Linux as well, or anything else you care to boot. Whoa! Hold on here for a minute or two. What you are saying there is not exactly true. To fully see 4GB's of installed RAM two conditions must be met: 1- The hardware architecture must allow memory to be mapped in area's above 4GB. 64-bit hardware and Intel's PAE permits memory mapping above 4GB area. 2- You need to use a 64-bit Operating System or a 32-bit one that is actually PAE aware so that it is able to address memory above the 4GB level. As usual, Microsoft have been dragging their feet with this. Although not fully acceptable, that this issue be present in Windows XP 32-bit might be somewhat understandable. That it be present in any Vista version is completely unacceptable! Your assertion that Linux is affected by this issue is not completely true. Linux is light years ahead of Microsoft on this issue. If your Linux kernel cannot fully see all the installed RAM you use a 64-bit or a PAE kernel. That the Windows XP kernel cannot fully use PAE and map above the 4GB area is a bit of a shame. That the Vista kernel cannot do it is an ongoing joke! As witnessed by the posts in these groups, and in many other places around the internet, the age of motherboard with 4GB's of installed RAM is here now, it's time Microsoft took its head out of the sand! For the benefit of those who don't understand why they can't see all the installed RAM this explanation from Tyan sum's it up nicely: The problem that you are seeing is based on an older architecture design for memory addressing. All the systems architecture up to this point were based on a maximum of 4GB of total memory. Nobody really thought, when this standard was designed, that this amount of memory would actually be in use. The problem that has happened is that you have PCI devices that require memory address ranges so that they can properly execute their commands. These address ranges were mapped in the upper sections of this maximum amount. Since nobody thought you would be using up to 4GB these address ranges started around the last 500MB of the memory ranges. This range is called the T.O.M. or Top of Memory range. This is the point in the bios where it places on hold the amount of memory that is required by the various PCI devices that are found on the motherboard. Thus when you have PCI cards or AGP cards installed on your motherboard these devices hold on to memory for their own use and take away from the maximum amount of memory that is available for other tasks. This amount of memory can vary from a little as 200MB all the way to 1GB of memory (or even more in select cases). It just depends on the PCI devices you have and the amount of PCI (including AGP) that you have installed all at once. There is really no way to get around this basic design limitation. The only way to get around these type of issues is to use certain new designs that have brand new architectures (i.e 64-bit designs) that allow memory to be mapped in area's above 4GB. The brand new Intel Xeon designs and the AMD Opteron designs are built around 64-bit technology. This is only ½ of the equation that you would need to find success. You would also need to use an OS that is actually PAE or PAE aware so that it is able to address memory above the 4GB level. To find out about PAE you can search Microsofts website for PAE (Physical Address Extensions) and it will explain this concept and what OS's actually are capable of providing this benefit. Windows 2000 and Windows 2003 would fit both of these criteria. Windows XP on the hand would not allow this type of ability. Microsoft has addressed this type of issue in the following Microsoft Article (291988) http://support.microsoft.com/default.aspx?scid=kb;en-us;291988 [end quote] DDR FAQs # 6 Why do I not see all 4GB of memory... http://www.tyan.com/archive/support/html/memory_faq.html John
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