No, I didn't see a 0401 bios mentioned anywhere, but they should make a fix since Vcore adjustment with the QX9775 doesn't work properly, as we know thanks to giorioprimo. Also AHCI/Raid doesn't seem to work properly for some people, especially when more than 4 drives are installed. Again, I don't know about that, I only got one DVD running in IDE mode... leave the Raid to a real controller

Well, back to your problem. I don't see how you could solve this without trying to swap hardware, piece by piece. Try another PSU, one stick of mem, a PCI video card, only one CPU, and finally another S771 CPU.
If all that fails, you should consider the possibility of a dead motherboard and rma :/

On a sidenote, I just finished operation "get rid of ing stupid aircoolers" - my 5420's are watered at last. Pics later or maybe tomorrow.. I'm kinda tired right now.