Okay so I am having a really aggravating PC problem. I came home from work one day to find that my computer was turned off. I thought that maybe the power went out, but none of the household clocks were blinking. So that ruled that out. I attempted to power on my PC, but nothing happened. No beeps, no video, no nothing…Just power. My motherboard has an LCD screen that shows error codes if there is a problem. So all it showed was two dashes (--) on the LCD screen. This means that either the mobo is fried or the CPU is dead. So I sent off my mobo to get a new one. Got a new one back, hooked everything up, still same problem. Okay then it’s my CPU. Sent it back to Intel, got the new one back, put it in, STILL same problem. So I disconnected everything except the power to the mobo in hopes of getting beep codes for missing hardware to see if that was the problem. NOTHING, all my PC does is power up and will not go through POST. Any ideas would be highly appreciated. This is killing me!

Computer Setup:
Windows XP Pro
Intel Quad Core 2.4 GHz
EVGA nForce 680i SE
2 GB Wintec AmpX 6400
80 GB Western Digital
GeForce 8800 GTS Video Card
Rosewill 750 Watt Power Supply

If you are sure that the new motherboard is connected to the power supply correctly , all jumpers are in correct position and cpu is in correct then I would try a different power supply. Just because it seems to power up does not mean the PS is good.