I do not believe, from all of the statements and arguments on this site, that 8x will hinder a 5770 at all. Ive read that a 5870 has a 1% loss when running on an 8x, 4% on 4x, and 24% on 1x. You should really be fine. plus that CF setup with 5770's should get you similar performance as a 5870 minus the memory bandwidth. less money too. In my experience, as limited as it is I saw no jump in playable performance from my 260 Black Edition to my 5850, just sayin.