I understand that for crossfire to work, you have to be using two or more of the same model video cards (aka two 6850 or two 5970).
But I was wondering if there was a big difference in using two of the same models, but different manufactures. Or, if there were differences between using a mix of modified cards.
Example: I am looking to buy a Sapphire HD 6850 Toxic which has a higher core clock, effective memory clock, and other minor adjustments to the card. I am then looking to crossfire later down the road.
Is there a problem running a crossfire with a Sapphire HD 6850 Toxic (with adjustments) and with a XFX HD6850 Black Edition (different adjustments) or a Gigabyte HD6850 (with no adjustments). Or do you get the best results using crossfire with identical cards from the same manufacture?
I hope I didn't confuse too many people with this question. But thanks for any help.
It's best to have them clocked the same. When I was using two 3850s some games had weird artifacts or behavior if both cards were not clocked the same when crossfire is enabled. It wasn't that common, but it really annoyed the crap out of me. I haven't had that with my 5870s (ones at 850 and the other at 870 since the OC card is cheaper now for some reason). The only game that did anything weird lately was Gothic 4, but I just set both cards to 870 and it was fine.
I say get the cheaper Gigabyte card and overclock it yourself, but it's up to you.
You can CF two of the same family cards, hd6870 hd6850 = CF, but both will run at hd6850 speeds because of lowest common denominator. You can not CF a hd6850 and a hd6950. As lont as they are family you can.