Hmm. What was the flash for? To be honest, thats where you went wrong.
Perhaps the wrong BIOS version?
Its late, I'm trying to think, but I'm sure thats what happened.
You have to be careful, if you were flashing, say as example the 6800 BIOS,
that would up your voltage .1 and could really screw your GPU up.
Try flashing the originaly BIOS or whatever driver version you were set at
basically your default software...then take it from there. But alot of people screw up their one quads when flashing, either producing a BSOD or lots of artifacts.