Hi, I just built a new pc and had it running for only a day when I decided to plug in the headphones and microphone to the front panel jacks. As I plugged them in the computer shut down instantanously with out any noise. I then tried to reboot it and when i hit the power switch it does absolutely nothing except the mobo light turned blue, no fans or anything else came on. I thought that perhaps I had a psu failure so i went out and got a hold of a new psu today and hooked it up and now when i go to turn on the pc the mother board light flashes and nothing else comes on. I took some of the suggestions such as removing a stick of ram and trying to boot it on, but still it does not power on.

My specs are:
EVGA 780i mobo
XFX Geforce 8800 GS
OCZ 2x2gig ddr2 64000 800mhz reaper hpc
WD 320gb HD
Samsung 20x dvd burner
antec 900 case
intel core 2 duo 6750
windows vista
psu's
first: antec trio! 650w
second: BFG 800w

One of the more common mistakes people make is mis-wiring of the front connectors on a build-from-scratch PC.

You have to make sure you look at the connectors and compare them with the connection diagrams provided WITH THAT MOBO. Not everyone follows the same convention, some manufacturers provide separated wires, others group them together, others label things differently enough to cause confusion, etc.

Off-hand I can't think what specific mis-wiring would cause the symptoms you describe just because you plugged-in some audio items, but I'd double-check that wiring first thing...all of it...not just the wires going to the audio connectors.

Some mobos also provide jumpers on the mobo that you have to either plug-in or remove depending on whether you are using the rear connectors for 5.1/6.1/7.1/8.1 speaker output or for the audio components marked on the bezel (e.g microphone, line-out, line-in, etc) Those jumpers change how the front wiring is configured.

Ok so I've read all of the replies but I dont think I'm having the same problem. I just built a new computer and hooked everything up properly. Yet when i plug in the power supply I get nothing, no fans, no leds, nothing. Everything is brand new and I've tried multiple outlets.

Any ideas?

the symptoms for my computer are very similiar but when i disconect the computer for awhile then i connect it again it turns on for 3 seconds then shuts off again. Please help.
thank you

sounds like you need a bigger powersupply.