"This article proves you can easily pair a Radeon HD 5870 with a Radeon HD 5850 and run them together in mixed CrossFire for improved gaming performance over a single card solution. That in itself is a small victory and a nice feature to have if you have a chance to mix and match cards like this for a performance upgrade down the road. One thing that shocked me was that the CrossFire gaming performance of a Radeon HD 5870 + 5850 was lower than that of a pair of Radeon HD 5850 video cards in CrossFire in all of our testing with the exception of one game. I would assume it is because the higher capacity card (the Radeon HD 5870) gets brought down to the lower one (the Raeon HD 5850) plus some overhead..."
http://www.legitreviews.com/article/1107/1/
