|The GTX680's require two 6pin PCIe connectors each. Have you properly connected ONE card only during your test? Have you tried the other card instead (I assume you do not have onboard graphics)? Does your power supply have the four required PCIe connectors? If not are you using the Molex Y connectors correctly? They each MUST be connected to two Molex plugs on different wire runs, NOT on two Moles plugs on the same wire bundle in order to get the correct amount of current.|
Do you have the 6Pin motherboard power connector as well as the 24Pin power connector plugged into the motherboard? edit: I just reviewed a picture of your motherboard, it has a 4 Pin connector, an 8Pin connector at the 'top' and a 6 Pin connector lower down. See your manual on powering all of these connectors. I am not familiar with a board this extreme.
Do you have a different power supply to test this system with? For just testing to post with one video card, any GOOD quality 600Watt power supply would work. Have you tried (yourself) to test the new power supply on a working computer to see if it actually works?
IF you can verify that the power supply works on another computer and another working power supply does not work on this computer AND you are correctly bench testing with just the minimal equipment (no post, no beeps, etc.), then either of these must be true:
The CPU is not properly in the socket (see aligning pins, etc).
The CPU socket has bent contacts (possibly from improperly inserting CPU).
The motherboard is bad.
The CPU is bad.
Review bench test procedures and if correct, remove and examine CPU & socket carefully, if correct, return to the store with the motherboard and CPU.
You have to be a little bit crazy to keep you from going insane.