System not Starting - Probably mobo? Or PSU?

[Dace]

Hi All,

 

I've ended up on these boards a hundred times via Google for various issues, I've tried begging the Goracle for advice on this but my querying skills aren't up to it. Tried searching the forums specifically for this issue, didn't find an answer that worked so far, so I'm sorry if this is a stupid query or has been covered before, I did try a search before posting.

 

The desktop was working fine last night. The last thing I did on it was a Deep Defrag and turned it off. This morning when I hit the power button, the GPU fan starts going at full speed and nothing comes on. No screen output at all.

 

I've openned her up and checked cables, re-inserting the GPU and Soundcard and ensured no dust on them. It's still happening. What I have noticed and this that a red light comes on behind the 8-pin power adapter on the GPU and stays on. It happens whether the adapter is in or not. I'm not sure if this is relevant, but with the mains power on there is a red LED at the bottom of the Mobo. A green light joins it when I switch the desktop on.

 

I do have another 8-pin power adapter home with a wide for the GPU, 4-pin socket on the end of it (the wires on it are yellow and black, just like the 8-pin one in use) in case it's this that needs replaced. And there are loose-hanging 4-holed sockets that this end will fit in that dangle down from the PSU. I've tried putting the spare one into two of these hanging 4-pin sockets and connecting it to the GPU but the same thing happens. As you can tell, hardware is not my strong point.

 

I cannot turn the computer off by holding down the power button, I need to switch it off at the wall mains.

 

So i tried taking out the GPU and connecting my monitor to the on-board graphics. It's alot quieter without my GPU fan going full speed, however no graphical output and it still takes the mains to get it off.

 

Once every few months it'll start with the GPU going full speed and need to be turned off and on again and it's usually fine, but in these cases it would go off by holding the power button down.

 

The machine:

 

Windows XP

Mobo: ATI 200

PSU: EZCool Socket 775 600W

CPU: AMD Athlon San Diago 4000+

RAM: 2GB

GPU: ATI Radeon x1900XTX

HDD: SATA RAID 160GB

Audio: Soundblaster Audigy 4

[Dace]

I forgot to add, it doesn't make any beeps when it comes on, but it usually does.

[Armageddon]

Dace can you try removing the ram cleaning the contacts with a pencil eraser then replacing then trying to boot the machine

[Dace]

I'll try it right now, I didn't think it would be the cause as it won't power off and just the mobo would be involved in this, but I'll report back in a couple of mins.

[Dace]

I tried putting it on without RAM, HDD or Audio card in - same issue. I've put them all back in, cleaned the RAM, and now no fans go at all. And there is a very high pitch but faint noise, possibly coming from the PSU. I know a bad RAM can result in a constant beep, it doesn't sound like that...

 

Anyway, I had to fight to get the RAM sticks back in. They need a fair bit of force/careful distribution of force fo get the clips to click properly. Not sure if I caused further damage, nothing broke that I could see and I wasn't battering them.

 

In any case, it's still not posting at all, just like before.

[Dace]

Maybe I was more of a dunce with the RAM than I thought, I took the GPU out of the way temporarily to let the clips properly relax, and this time they went in ok. And I'm back at square one again, original problem has come back.

[Dalo Harkin]

You mentioned you ran a defrag before the system stopped working (there was a post recently that I advised against using defrags, look it up at some point)

 

Now you say that you cannot shutdown the PC via holding the switch, if this is recent and it used to then I would say the MOBO or PSU are the suspect.

You say that the fans run at full speed now, this happens when the BIOS is reset*, due to a fault.

Have you tried unplugging the PSU power cord from the mains and then popping the CMOS battery out for 30 seconds, reinsert the battery and then connect the power cord and try and power up.

 

*Note that if the BIOS has been reset then the MOBO will revert back to using the onboard video as opposed to an add in card.

 

Hope some of this helps you

[Dace]

Thanks for the advice!

 

I took the cmos battery out, tried booting without it, still no POST.

 

Left it out for a couple of mins, put it back in, still no POST.

 

I guess this is starting to look very much like an upgrade/replace.

[Dalo Harkin]

You have to unplug from the mains too when you remove the CMOS

have you checked and re checked ALL the wires including the ones that connect the case to the MOBO, as they have to be in the way as in + -

[Dace]

I had the mains off and the power cable removed from the PSU.

 

I've checked all the cables before and tried taking out/putting in as many as I could, i'll take another look at them and make sure they're aligned properly.

[Dalo Harkin]

The case power/reset switch wont work if the cables are the wrong way round.

[Dace]

I've gone over them again, as far as I can see they're ok. It was doing this before I openned it up and checked the cables, so I'm confident they're properly fitted as far as I can see. The only cables I can't be sure of are all the ones that disappear into the PSU. I'm not fully sure on how everything looks when it's properly in anyway, but I've been in the case a number of times previously and things seem in place.

 

I don't have any proper PC tools to test the PSU or anything so I can't rule that out either.

Edited July 16, 2010 by Dace

[Dalo Harkin]

If you have a friend or someone who uses PCs then borrow a PSU to test, if that doesnt fix it then I would say its the MOBO