Computer won't boot at all. Doesn't even get to POST

[sygyzy]

Hi,

I consider myself a fairly savvy computer user, having built my own systems since the mid 90's. Anyway, the other day I cleanly shut down my Windows 7 system. The following morning, I went to turn it on and nothing happened. It didn't beep and nothing went on the display (not even BIOS).

I didn't have time to deal with it til this past weekend. I opened it up and pushed the power button. The CPU fan spun for about 1 second then stopped. After this initial spin, any subsequent pushes of the power button results in nothing happening. The only way to get any response out of it is to unplug the AC power cable and replug it back in. Then, I can get it to spin the fan for 1 second again. I believe the graphics card fan spins slowly at this time too (1 second).

I tried pulling the GPU (ATI 5770?) to see if that was the problem (I have onboard video). I also pulled out one RAM chip to let it boot off just one DIMM. I also swapped the DIMM chips so it would try the other one solo. I also reseated the CPU and HSF.

There was no power surge, brownout, or (rolling) blackouts in my neighborhood. I have the PC plugged into a nice APC battery backup (not a cheap unit). There is no charring or smell of smoke. And, like I said, the system was shutdown cleanly - no power cord being jerked or anything.

Does anyone have any ideas what this might be?

 

[thelastjuju]

Well, you've tried pretty much everything besides the two things that usually result in this problem:

>Dead/dying PSU
>Dead/dying MOBO

Probably much easier to find a spare PSU to try rather than a spare MOBO, so if it still doesn't work with another PSU you can safely narrow it down to a bad MOBO.

edit: just realized I mixed up MOBO and PSU in last sentence, oops. fixed now.

 

[sygyzy]

I know it's certainly possible but I rarely accept the possibility that things "just die". I mean it's probably happened once in my life where "for no reason" a device just ups and dies. Does this really happen? No power surge, no blackout, no water poured on PC and the motherboard or PSU just dies?

 

[lakedude]

Hi,

I consider myself a fairly savvy computer user, having built my own systems since the mid 90's. Anyway, the other day I cleanly shut down my Windows 7 system. The following morning, I went to turn it on and nothing happened. It didn't beep and nothing went on the display (not even BIOS).

I didn't have time to deal with it til this past weekend. I opened it up and pushed the power button. The CPU fan spun for about 1 second then stopped. After this initial spin, any subsequent pushes of the power button results in nothing happening. The only way to get any response out of it is to unplug the AC power cable and replug it back in. Then, I can get it to spin the fan for 1 second again. I believe the graphics card fan spins slowly at this time too (1 second).

I tried pulling the GPU (ATI 5770?) to see if that was the problem (I have onboard video). I also pulled out one RAM chip to let it boot off just one DIMM. I also swapped the DIMM chips so it would try the other one solo. I also reseated the CPU and HSF.

There was no power surge, brownout, or (rolling) blackouts in my neighborhood. I have the PC plugged into a nice APC battery backup (not a cheap unit). There is no charring or smell of smoke. And, like I said, the system was shutdown cleanly - no power cord being jerked or anything.

Does anyone have any ideas what this might be?

PS or MB, my guess is PS. Do you have another Power Supply to tryout?

 

[lakedude]

I know it's certainly possible but I rarely accept the possibility that things "just die". I mean it's probably happened once in my life where "for no reason" a device just ups and dies. Does this really happen? No power surge, no blackout, no water poured on PC and the motherboard or PSU just dies?

Yeah, sometimes stuff just happens for sure.

I have repaired hundreds of computers and the power supply is one of the most common parts to fail. Only thing worse was modems after a rain storm back in the dial up days. Haven't seen a bad CPU since the Cyrix days. Now that both AMD and Intel have thermal sensors they generally keep themselves from burning up. You have already more or less ruled out RAM (and I think you would get farther along in the boot process if it was RAM).

 

[sygyzy]

I don't have another PS but it was the one component (other than the case) that I didn't change in my new system overhaul. It doesn't bother me to spend $60-100 to get a new PSU anyway.

 

[Vinwiesel]

You need to disconnect everything from the power supply and see if it will turn on by itself. Easy to do, and if it doesn't come on you know for sure it is the problem.
If that works, try only the motherboard and see if the supply stays on. It could be a Hdd, a pci card, or just a random connector shorting to the case somewhere. It doesn't have to be a high power component to trip the supply.

 

[sygyzy]

How do you make a power supply turn on by itself if it's disconnected from the motherboard? Can you tell me what pins to short?

Edit: I see, short green to black. Do I leave the clip in there or remove it once it's on?

 

[Vinwiesel]

The PSU should turn on as soon as you jumper the green to black. It should stay on as long as you have these two connected.

 

[sygyzy]

I left the PSU inside the case an unplugged the power cables to all hard drives, graphics card, and the two (12 + 6?) plugs to the motherboard. I shorted green and black together and the PSU fan spun for half a second then stopped. No noise or anything.

I take it, the power supply is dead?

 

[sygyzy]

Just an update in case anyone is interested - I bought a new power supply and installed it and now my computer works! I am so happy. Thanks to everyone for your help.