GA-965P-DQ6's will not POST

Have two GA-965P-DQ6s. One is in an Antec Sonanta II case the other is in an Antec 900 case with an Antec 550w Truepower supply. Both systems have the same components. Corsair CM2X1024-6400C4 memory, EVGA 7900GS video, Seagate 320gb Sata drives. Just built them and neither one will POST. Both do the same thing. Lights on, fans spin a little then shut off, then starts again over and over. I've taken everything out except CPU and the speaker gives a continuous series of shot beeps which the manual says is a power error. I can't believe both power supplies have problems. Does anyone have an idea about this one? Any help much appreciated. One more thing, if I disconnect the additional ATX12V connector the lights stay on and the fans keep spinning but there are no tones. Guess there is no power to the CPU?

 

Oh, forgot to mention the CPUs are E6600s.

 

I have the same problem with my system:

Gigabyte GA-965P-DQ6
Intel Core 2 Duo E6400
OCZ DDR2 PC2 6400 in slots 1 & 3

I don't have time to troubleshoot it right now but I'll take a look at it later and let you know what I find.

 

Turns out both boards are defective. I returned one to Newegg since I had the packaging. Got a replacement which works fine. Unfortunately I threw out the package for the second (whoops) so I had to send it back to Gigabyte to be repaired or replaced. They said it was clearly a power problem. The one board I have working now is great I must say but it was a drag to get where I am now.