Computer refuses to turn on

[panta]

I sent this to Corsair Tech support:

Example scenario

I turn the PC and monitor on. I use it for two hours.

I turn the PC and monitor off. I then decide I want to do one last thing on the PC, and turn it and the monitor back on immediately. The PC appears to start up, but then shuts off 3-5 seconds later. It stays off for 1-2 seconds, then turns on again and stays on except with the monitor in standby (blinking light on monitor, no picture). I give up and go to bed. The next day I turn the PC on and it works, but the same issue arises when turned off and on immediately after use, with the PC apparently only willing to turn back on properly after being left for a while (not sure how long) after being shut down.

There are no known problems when the PC is running - games, web browsing, benchmarks - all appears to be fine.

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After doing some searching I came across this: http://www.reddit.com/r/hardware/comments/7d3fr/can_someone_explain_the_capacitor_drain_trick/

2) hold down power button for a while (I did a minute, I think I've heard 30 seconds will work). This drains the capacitors fully.
This did nothing. And it was not, actually, discharging the capacitors that fixed it, but rather cutting power to the microcontroller. You could also have unplugged the motherboard from the power supply, and it would have fixed it.

Having read the above, I decided to test this out. I turned the PC off, and, as usual, it refused to turn back on. Next, I shut it down, remove the side panel, remove the 24-pin motherboard connector for a couple of seconds, re-insert it and then turn the PC on. It worked - the PC turns on properly.

I then tried the holding the power-on button down for 30 seconds method and that also worked.

So what the hell is the problem? Power supply? Motherboard?

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Specs

Q6600

4GB RAM

TX 750

4870

P5Q Pro

WD6400AAKS

Antec 1200

 

[jiminator]

I hate when my wife refuses to be turned on...

but to your question, check to see if your power supply has a button in the back. as a test try using that to turn off the system. capacitors should drain fairly fast.

really I don't know what that would prove. Some PSUs leave the fan running for a few seconds after the power is turned off, to prevent thermal spikes.

 

[panta]

That also works, sometimes. I usually have to turn it on and off several times and sometimes it doesn't work at all. The easiest and most sure way seems to be holding the power button down for ~30 secs to "cut power to the microcontroller".

I really would like to fix it though and not have to do that.

 

[panta]

I really don't know what to do here.. any advice?

 

[Shadowssong]

Do you have any spare parts or friends that can lend you a part for testing? I would say swap as many parts as you can too see where the problem lies (psu first)