About 2 weeks ago my system looked like this:
*P5K3 deluxe wifi
*forgot the CPU, intel quad core
*Corsair 7-7-7-20, 1066 mhz 1gbx2
*OCZ 650 watt PSU
*Gforce 8800 GTS 512 mb
Then I upgraded my memory and an extra hdd
* Mushkin, 6-8-6-24, 1600 mhz 2x2
After a couple days I had my pc turned on when I went to eat, and when I came back my pc was turned off. So when I tried turning it on only the fans ran for about 0.5 seconds and thats all that happened.. the LED light on the mobo was on. But I figured something was wrong with PSU somehow.. so I tried a new PSU a CM with 750 watt, with the same result...
I tried resetting the BIOS with clearing the CMOS
Tried only having my mobo plugged to the power
Running old memory, and also only running only 1 module
I had the same problem with my old PC. I was a little short on cash and bought a cheapo PSU and came back one day from school and it was off. I tried to turn on, it wouldn't post or anything the fans would just barely spin. I was looking at some stuff and found some bad surface mount capacitors on my board. You can usually see a browish fluid coming out of them when they are bad.