I wonder how much heat this this generates? How does it stay cool? I have two GTX 670s in SLI and they can get to about 60 degrees with a gap between them... Th

I wonder how much heat this this generates? How does it stay cool? I have two GTX 670s in SLI and they can get to about 60 degrees with a gap between them... This many cards sandwiched so close must get really really hot. I don't see any water cooling...