PC crashed and will no longer boot correctly

[alexthetitan]

I built my PC in late October of 2011 and until now I have had very few issues with it. However while playing a mod for Arma 2 yesterday my PC crashed. I assumed that the crash was caused by the game so I simply rebooted and went on my way. Unfortunately, after playing Arma 2 for only a few minutes today my PC crashed once more. However this time it would not reboot properly. When I turn it on the fans spin up, as well as my HDD yet there is no beeping sound made, the LEDs on the motherboard don't light up, and there is no video signal to my monitor. Furthermore I can use the power button on the motherboard to turn on the computer, but neither the reset button on the motherboard, nor the reset button on the case are functional. What can I do to remedy this situation? I have already tried resetting the CMOS, as well as removing and subsequently replacing the motherboard battery to no avail.

Below are my relevant specs.

Motherboard: ASRock P67 Extreme4 Gen3

Video Card: MSI Twin Frozr III 570 overclocked to approximately 900 mhz

CPU: 2500k overclocked to 4.6ghz

PSU: XFX Pro 850w

 

[alexthetitan]

I disconnected and then reconnected the CPU power connector which seems to have resolved the problem. It would still be nice to know what caused this as I do not see how it could possibly have come lose while the PC was in a static position.

 

[smorizio]

i would check to see that your cpu fan and power supply fan are working. i would use hardware monitor to log your temps.
it could be the pc shut down to save the cpu.