About a month ago my video cards started massively overheating for no reason, so I sent them to get fixed. They ended up just replacing them, but my new ones don't seem to be working right. They're the same model(6800gt) with all the same specs(checked in everest), but either no SLI option shows up, or it says I need to remove SLI incompatible cards. I figure this should be a BIOS issue, as I tried reinstalling the drivers, switching the cards between the two ports, and nothing helped. So I followed the guide on this site, and after a little problem solving I got nvflash to work from a bootable USB stick. However, when I try to do anything with it, it says that it can't find any Nvidia video adapters. Could there be something I'm doing wrong, or is it a flaw with the cards? Thanks for your time, any help will be greatly appreciated.