PCI Slot help!

[Top Dog]

Hi guys, I don't know much about motherboards, and less about pci slots. I have a Gigabyte GA - P55 - US3L and It has 2 pci express slots, one running at 16x and the other at 4x. I am planning to crossfire 2 ATI 5850 cards. Would it work, and would the two cards run efficiently? Or would there be bottlenecking? Do I need 16x - 16x or 8x - 8x in order to crossfire? It says that the motherboard supports crossfire, but i am a bit wary. All input is appreciated, Thanks. Also, heres a link to my motherboard: http://www.gigabyte.com.tw/Products/Motherboard/Products_Spec.aspx?ClassValue=Motherboard&ProductID=3168&ProductName=GA-P55-US3L

Also, I have 4GB Corsair DDR3 Ram at 1600hmz, And an i5 750, 2.66ghz quad. Incase it helps. Thanks again.

 

[GhislainG]

You should read this on Tom's: http://www.tomshardware.com/reviews/p55-pci-express-scaling,2517.html They used HD 5870 instead of HD 5850 video cards.

 

[welshmousepk]

if its only x4, then no, you cannot crossfire without a bottleneck.

16x is ideal, but 8x is only a minor bottleneck on all but the most powerful cards. x4 will bottleneck them severely. you would be much better off going with a single more pwoerful card (a GTX 480 or maybe a 5970)