Originally Posted by trumpet-205
Oops. My bad, I meant no SLI.
However, the second PCIe operates at x4. While you can do CF with x16/x4 configuration, you really don't want to. x4 will hold back CF performance a bit. 990 allows you to CF with x8/x8, which is better than x16/x4.
The 970 is x16 x4 however its a "electrical" x4 witch I believe means its wired off the southbridge instead of the northbridge like a x8 or x16.
The 990FX is x16x16 SLI or CrossfireX with additional PCIe slots at x8 or "electrical" x4 (just got the 990FXA t weeks ago so I had to read a lot)
Biostar is noted as a low end brand however in recent years have really tried to break away from with pretty good success. If your looking at Biostar the TA990FXE is tested and true. If you are going AMD for a new build I would also recommend the Phenom II 960t. It may unlock to a full x6 but at x4 it still will pull better performance that the FX 6100.
Good luck with the upgrade