PC shuts off, has trouble rebooting.

I've been having a problem as of late, where the computer will shut off completely with no warning, attempt to reboot and fail. The power button light will light up, the fans whirr, but other things don't seem to be getting power. The card reader doesn't light up, nothing beeps, and the monitor doesn't detect anything and goes to sleep.

Often, I have to try rebooting five or six times before anything starts to happen.

Sometimes I can go for weeks without the computer shutting off, other times - like tonight, the shut offs occur almost every 5 minutes.

Games or HD video don't seem to cause the PC to shut off any more than usual. It shuts off even when I'm not using it.

Any suggestions on what could be the problem?

Computer Specs: Gateway Win 7, Intel Core 2 Quad Q8300.

 

what are you running
video card brand and model
cpu
m/board
ram
power supply
brand
model
wattage

check the listings in the bios for 12v line voltages and temperatures and post them

any bsod error messages

no error messages usually point to heat or power as the problem

check the m/board for bad caps

http://www.badcaps.net/

gateway are known for their problem m/b's and psu's