what power supply are you running? did you make sure to plug in the 8 pin CPU power on the top corner of the board?
I would swap power supplies and see if that helps, SeaSonic and Corsair makes excellent PSU. Ram voltage should be 1.5v, check the bios make sure it's set at 1.5\auto, however it sounds like a failing power supply to me since under load it fails.
Sure enough, it was the power supply. In retrospect, I guess there are many possibilities that could have been worse. I did pick up a Corsair 800, it seems to be happy now. The old supply was a 700, and had been powering my old system for about 2 years, so I guess it either went bad RIGHT at the time I replaced motherboards or this new motherboard has a much tighter tolerance for voltages. In any case, it's working so that's good!
Also, about the RAM, I had heard that 1.5 is where it should be, but this RAM (G-Skill Triton) calls for 1.65. I'm not sure who to make happy, the mobo or the RAM! I'll set it to 1.5 and see how that goes.
Thanks for the response!