Computer will no longer power on.

[thurman86]

System specs:
Processor: Intel Core 2 Quad Q6600 Go SLACR
Motherboard: EVGA 780i
Memory: 2x1Gb Corsair Dominator DDR2 1066mhz
Video Card: 768mb XFX Nvida 8800 GTX
Hard Drive: 2x 74gb Western Digital Raptors on Raid 0
Power Supply: Ultra X2 750w

I have had this system for almost 2 years now. Yesterday i used the computer for a few hours and left home. When i came back home the computer was off, i figured the power might have went out while i was gone. I hit the power button to turn it back on and got no response. I checked all connections to make sure nothing had come loose and made sure the surge protector was on and working. The motherboard LED is lit up and if i turn off the surge protector it goes off as normal. One thing that i did notice that was out of the ordinary. When i was first checking the connections i noticed that the NIC connectivity light was on and my router was also showing the LED as though it picked up on the computer as being on. After i turned off the surge protector and turned it back on the activity light on the computer and router were out. Other than that everything else seems normal. I have not had time to dig into it any deeper but wanted to see what suggestions anyone here may have.

 

[False_Dmitry_II]

My first guess would be to try a different power supply and see if that one is bad. I think I've seen other posts with that model that died.

 

[Paperdoc]

You could try something simple that works for me. On rare occasions my machine will not respond at all to pushing the front panel power button. To cure it I either disconnect the power cord or simply switch off the power switch on the back of the PSU, and LEAVE IT OFF for at least 30 seconds. This deprives the mobo off ALL power after the PSU's capacitors drain down. When power is restored and the front button pushed, it's back to normal again. I hypothesize that somehow the small BIOS loop that runs while it's "Off" to watch for a power button push gets locked up and cannot respond. A complete cold restart solves it.