Press power.....nothing happens

[freelander]

Hi All,

 

Apologies, as I'm sure this question has been covered somewhere before but I can't find it. So I'll ask the question and if you can either answer it or point me to the relevant thread I'd be so very grateful.

 

When I try to power up my pc nothing happens, the fan doesn't start up, it's as if the thing has no power at all. I've swapped the power supply for one that is known to work and again nothing happens.

 

I think the clue could lie within the CPU fan and CPU. When I opened the tower up I found the CPU fan to be very clogged with dust so I cleaned it out. Non of the capacitors look to be bulging or leaking.

 

So I fear the CPU is to blame, but I really don't know enough about pc's to be sure. What else could I try?

 

I had the pc built for me by a capable chap, who I've lost touch with.

 

PSU eagle DR-B350ATX

CPU fan Sanyo C33218-002

MOBO GA-8PE667 ultra2

Phoenix dual bios.

 

Thanks in advance.

 

F

[KenB]

Hi and welcome to fpch

 

If you have changed the PSU for a known good one then I suspect that the problem lies with the motherboard.

 

Switch off at the wall - leave the plug in to maintain the earth / ground.

 

Take all cards ( RAM / Sound / Video etc etc ) off the motherboard.

Disconnect the power connections to the DVD and Hard Drives.

Disconnect the DVD and Hard Drive data cables from the motherboard.

 

Leave only the 20(4) way connector from the PSU connected.

 

Switch on.

You should, under normal circumstances, get POST beeps.

(assuming that your onboard speaker is working and you used to get one beep after switching on ).

 

If you don't get POST then your problem lies with the m/board ( assuming your PSU is good )

 

If you do get POST then put the cards / connections back one at a time until the problem is replicated.

[PseFrank]

EDIT: FOLLOW KENB'S ADVICE FIRST

 

Hi Freelander, and welcome to Extreme Tech Support - Free PC Help

 

It could be that your power button or the wires from it are defective. There is a way of testing if that is the case......but it is a little fiddly to do. By what you've said you are obviously happy to delve into your tower. But if you have any doubts about carrying out the instructions below, then I would suggest you take your PC to a repair shop. (That is unless someone else here has another remedy)

 

I'm assuming that you have a Reboot/Reset/Restart button on your PC. That being the case, you can swap your Power button motherboard connector with the Reset connector. If my hunch regarding the defective Power button is correct...you should then be able to start your PC from the Restart button.

 

In any case trying this will not harm your computer.

 

1) Disconnect the power cable from the PC and remove the side panel... take the usual precaution of touching the metal casing before going near the motherboard.

 

2) Somewhere on your motherboard you will find the Power button connector and the Reset button connector. These small connectors are usually marked POWER SW and RESET SW. Make a note on paper (Always do this) of which connector goes where on the motherboard.

 

There will be two wires going to each connector. (One coloured & one probably white) The coloured wires will be different for each connector.

 

3) Remove both of the connectors from the motherboard and plug the RESET SW connector onto the small pins where the POWER SW connector was. You can leave the power switch connector unplugged.

 

4) Plug your power lead back into the back of your PC. Your computer should now start as normal.

 

Please post back here if you have any questions, or indeed to let us know how you get on.

Edited September 12, 2010 by PseFrank

[Dalo Harkin]

Your looking at this

http://img.hexus.net/v2/motherboards/intel/asus/900/Pins.jpg

 

Also note that there is a + and - for EVERY pin furthest left red is +

[freelander]

Thank you very much for your advice.

 

I'm going to attempt the reset option this afternoon, as that suggestions seems the quickest and easiest to do.

 

I'll let you know how I get on.

 

Thanks again.

 

F

[freelander]

Hi,

 

Tried all the suggestions and still nothing. So I guess KenB's thoughts were on the money and the Motherboard has a problem. I've taken everything off the motherboard bar the CPU and fan.

 

It is an odd one though because the machine was working absolutely fine and I turned it off as normal. When I came to power it up again a while later, there was no response.

 

Do any of you have an idea/recommendation on a motherboard and cost?

 

Thanks for your help.

 

F

[Dalo Harkin]

Have you checked and double checked all the power connections to everything, the 20/24 pin ATX (and the 4/8 pin one)

 

when you do this and turn it on, at the very least there should be an LED on the MOBO somewhere that lights up.

[freelander]

Hi Dalo,

 

There's no lights anywhere on the MOBO. The PSU and all its connectors were probed and it was found to be ok. I still replaced the PSU with another and again nothing happened. I've since put the original one back in and then tried all the suggestions here. I've just tried another PSU and connected to the motherboard and again nothing at all.

 

I'll have a look at the power switch in more detail to see if the whole unit has come adrift, would that explain the reset power/main power reversal from not solving the problem? By the way the connectors on the F panel named, reset switch and soft power switch were the one's I swapped. There was another named message LED/power/sleep LED, I figured that one supplied power to the light on the front of the tower, so ignored it.

 

Thanks

 

F

[Dalo Harkin]

It would yes, if the connectors are all not correct as in + and - then the buttons dont work it would be stuck on of off (depending on the orientation of the wires) :)

[freelander]

Checked all the connections and they seem fine. Would you agree that the MOBO is at fault or is there anything else I could try?

 

F

[Plastic Nev]

Just one thing left and then yes the mother board.

The main molex multi pin plug from the power supply that sits on the motherboard, pull it off and inspect all the pins, particularly on the motherboard and where they go into the board itself, look for brown burn markings on the board round the pins and also discolouration of the pins themselves.

 

If either you find burning or even a pin that seems loose, sometimes this can be sorted by someone with a very steady soldering iron, but don't be too hopeful as damage may be spread if burnt.

 

If no obvious problem with the molex I think the mother board at this stage unless someone else has any other ideas.

Nev.