I have a Sapphire HD 6850 and want to buy another one and put them in crossfire, trouble is I can't find a Sapphire version. I have found an XFX HD 6850, my question is, can they be put in crossfire and would I notice an increase on my FPS during gameplay?
Yes you can Xfire them. The increase is dependent on the game. Some games scale great, Some well, and some not at all. Very few are even worse. (This is generaly older games and most have been patched in some way)