I am putting together a new computer and I was wondering if I should go for two 5770 crossfire or a 5850? The reason I am picking between the two is cost as the 5870 is a lot more. It will be a i7 930 with 6 gig of 1600 RAM on the Gigabyte GA-X58A-UD5. Also the power supply I am looking at has 2 PCI-E 8 pin connectors will that work as 6 pin that the 5770 and the 5850 needs? Thank you.