Im not an expert, but I have some basic knowledge.
This is a very weird problem, it happened since 2 weeks and still occurring.
The 1st time it happened the PC goes black out and when I press the power on button, no sound no light no nothing happens. Its not going through a proper shutdown, its like you just suddenly pull out the plug from socket.
I suspect its overheat, so I waited 20 minutes or so and try again, still nothing.
Then I try reconnect all the power cables connecting to the PSU.
Put all back together and try turning on, the PC is alive again!!
The PC was working normal again, its as if the black out didn't happened.
A while ago I on the PC for not more than 10 minutes, the weird problem comes again.
That means it is not overheat, since I only have my PC turned on for only 10 minutes.
My PC casing is semi transparent, I can see some part of the component inside.
Normally there is a orange light at the switch button that is on the motherboard.
Now when the weird problem occur, I can see that the orange light is gone.
Then I would off the main switch of the power cable connecting to PC for 20 - 40 mins.
After that I switch on the main switch back again, I can see the orange light on the motherboard again.
When there is no orange light on the motherboard, nothing will happen when I press the on button on the PC, no sound no light no movement.
That means when the weird problem happen, there is no power at all, and when there is orange light means I can on my PC.
So long as the weird problem occur, I just switch off the main switch on the socket for 10 - 20 mins.
When I want to on the PC again, I switch on the main switch then on the PC.
The PC will run like normal for 10 - 30 mins, after that it will go blackout.
Now my PC is like a time bomb, anytime it will go black out on me.
Do you know what is the component that is causing the problem?
I suspect its the power supply unit problem though.
Here is the PC spec if it might help:
Intel core i7-920 2.66GHz 8MB
ASUS P6T SE (GREEN) LGA1366
Cosair DDR3 2GB x 3 1333Mhz CL9
WD Caviar Green 500GB 3.5" 32MB SATA II HDD x 2
Palit GTX285 1GB DDR3 PCI-E
Andyson 800W modular PSU
Samsung SH-S223 22x SATADVD Writer
MicrosoftWindows 7 Home Premium 32bit
Probably the power supply; just because one voltage is being supplied, this does not mean the rest are. Even if that PSU was not causing problems, I would recommend getting a nice corsair to prevent problems in the future...a 500W corsair should make a lot more power than some generic 800W.