PC won't power on if I haven't powered it on it a while

[CalvinHobbes]

I have a very weird problem. My game machine won't power on if I haven't used it in a while. Sometimes it will sit for a month or two and then when I go to power it on, the fans spin for a split second and then nothing happens.

I have to disconnect the power cable (from the PSU), disconnect the power cables going to the motherboard and plug everything back in. Eventually it will power on and will work fine from then on. Once I leave it off for a while, it does the same thing the next time I try to power it on.

Could it be that the power supply holds a charge for a while that allows it to power on, but after sitting a while, it doesn't have that retained power?

Could it be the mobo?

 

[furballi]

PSU or MB. Try another PSU. If okay, then the problem is most likely the MB.

 

[wpshooter]

The first area that I would check would be the CMOS battery.

 

[GalvanizedYankee]

I think it might be the PSU. The PSU does not need to have it's caps charged to work. True, caps can hold a charge for weeks. But that is not the issue.
If the PSU is old (5years+) or the caps have started to leak abit, they will fall way out of spec when cold.
Once the rig is up and running, I bet there is no issue if put in standby for two days, then used again. This is because the electrolytics stay warm. Try warming up the PSU with a hair dryer set on low. Then try to boot. If the machine powers up, remove the PSU and open it for inspection if it's out of warrenty.

My garage TV is a 25+year old Hitachi. It takes two hours to settel down on 40F days. During 85F summer days it acts near new. Reason? Dried out electrolytics, probably capacitors.

...Galvanized

 

[CalvinHobbes]

The PSU is only a year old and still under warranty. If there's a way to open it without voiding the warranty I'll do that.
One thing I did notice is that the back of the PSU was warm even though the PC hadn't been used in a month. Maybe that's normal.

 

[GalvanizedYankee]

Someone correct me if I'm wrong but the PSU should build very little heat when the rig
is powered down. If your PSU is warm to the touch once it's been off for several days,
there is a problem. PM jmdeathsquad. Tell him I sent you. He just bought a Zippy/Emacs
for his home rig. He opened up the TT PSU he removed. It had been giving no problems.
He found several leaking caps. jmdeathsquad does comp maintainance for a living and is
finding lots of problems with electrolytics on boards and PSUs.

Try to look inside with a flashlight. You know the drill, bulging, swelling, tilting, leaking from
the top or bottom, maybe the tiny aluminum top is convex.

...Galvanized

 

[Ike0069]

Calvin,
I can almost guarantee that it's your MB. As soon as I read your title, I said to myself, "I'll bet he's using a Neo2 Platinum".

This is a definite trait of this board for some reason. I've never heard of a reason or a fix, but you seem to be lucky. When it fails to start, they usually never start agin and have to be RMA'd. I still have a Neo2 that has been RMA'd twice (once for this particular issue). It's a great board, but sometimes once they go to sleep, they just don't ever wake up. Exact same thing happens that you described. The fans start to spin, then just stop and it's dead.

For this reason, I never shut my Neo2 down (only restarted when necessary) when it was my main PC. Now that it's a back up, I shut it down every night but I'm still hesitant to leave it shut down for a long period of time.

My advice would be to try and run it more often. That seems to be the only answer I have found for this unique problem.

It does sound like you also have a PSU problem though. It defintiely shouldn't be warm when not in use. There is something odd going on there.

 

[furballi]

The PSU should remain cool to the touch when the PC is OFF. Max power draw is around 15 watts with the PSU switch ON after you shut down the PC.