Amen, those 290s aren't all that efficient. They're not folding currently though, I stopped them before the challenge. But I need to fire them up again to hit 30M soon.
. The main reason I don't fold as much as I'd like is the whole power issue
If I build another rig, it'll be a dedicated Cruncher with power efficiency in mind, hence my interest in the Xeon chips. This is particularly important for me because summer is already upon me down here with the heat already intolerable. It's going to be an expensive summer with the AC and everything else.