That's a NICE system! I've got the same case. But I've only got a single GTX580 Ultra in mine. I had a GTX590 for a while, but had nothing but problems with it, and eventually returned it for a refund. One thing I have learned about EVGA is that you really don't want to be the first on your block with one of their new products. So when they come out with their 700 series, I'll think about getting one of their 600 series boards.
Do you play any games on that rig?
