Computer wont turn on...sometimes?

[DarkMatterDM]

A strange thing happened to me...my computer will only sometimes turn on and work properly. I have tried to isolate the problem to no avail. I attempted to boot up the machine with each device unhooked, even took out the motherboard and checked for any shorts, but could not find any. It has crossed my mind that my MB or PSU could be faulty, but how can it be if it runs just fine after I manage to get it to turn on? The only way I can get it to turn on is by pushing in the power button and hope I get lucky. I tried interchanging the reset and power button connections to the MB, but that did not fix the problem.

The only thing I can think of is that there is some short somewhere in the system causing a problem. What things could cause the MB to be grounded out? I had to install a new I/O plate in chassis when I first built it...could this cause a short if it hits the MB? I can try to push the power button for 30min, walk away for a while, come back later and it starts on first try. Anyone have any suggestions?

Computer stats:
AMD Athlon64FX2 4800+Toledo
2GB Corsair PC-3500Pro
Asus A8NSLI-Deluxe MB
Thermaltake Armor8000 Chassis
2x eVGA Nvidia7900 GT's
SoundBlaster Audigy 4
XG Duro 900 PSU
Asus CD/R/RW/DVD combo drive

[EzyStvy]

The power button on the case could be the culprit.

[ktkendall]

One way to isolate that trouble would be to go inside there and use a screwdriver and short the same 2 pins togother momentarily the the power switch hooks into and see if the problem persists. If not then it's the switch, if it also happens that way then it is likely power supply or motherboard. Those switches can get dirty and the contacts can be not making good contact due to dirt and dust getting in there.

[rjfvillarosa]

Has this happened since the machine was first built?
How old is that case?
Does Kt's suggestion of disconnecting the switch and shorting the mobo pins work?

[lillac]

I am getting a very similar problem to DarkMatterDM. I can press the power button on and off for ever and all that happens is the PC powers up, cpu fan, disks, cd drive everything is getting power but nothing actually happens. Then walk away for 30 mins and try again and hey presto the graphics card pops up then the bios and we are in business. Driving me mad.

I left it on last night, it downloaded an automatic update from MS and rebooted so when I arived at my desk this morning I can here the fan and disks but there is no life, it took me forty minutes to get it to boot up.

would shorting the power button still be an option in this situation?

or any other ideas??

TIA

[ktkendall]

Lillac:
Best to start your own thread so we can address your problem without interfering with the original one here, but yours sounds different because your getting the fans and all to start whereas he is not which is why his problem may be the switch itself but yours is not because the fans startup everytime you hit the switch, so that eliminates the switch itself as the problem.