Alright, I think (I hope!) that I've found some stable settings on the vid cards. Kept getting a crash when folding after several hours and then my ppd would be cut in half due to the card going to 2D clocks.
Got two 280s and the 9800 GT running for about 21k ppd (in HFM.net)
Now to RMA the two broken cards and get to building the next rig. I might have to try VMWare again to get my 920 folding, but WCG is just a lot easier to do on the CPU lol