ATI lists 8GB of memory as the requirement for CFing cards. I don't see that having anything to do with the issues or the high temps but it is something worth noting.

I'd still like to know what driver version you're using. There are a few tools out there for driver removal but I can't recommend those and feel a good un-istall/reinstall is safer if you're interested in trying that.

I will fully and freely admit that I'm quite the tinkerer and after un-installing the drivers I would probably put the Sapphire in the top slot and the XFX in the lower slot with CF off and no bridge on the cards internally and see what they looked like after reinstalling the latest drivers. Probably a lot of unnecessary tinkering that may or may not change anything but like I said I enjoy trying things and that is where my mind takes me given what you've described.