2 x 5870 w/ PCI-E x16(x16) & x16(x4) mobo

[alexdrans]

I have the Gigabyte 880GA-UD3H motherboard (http://www.overclockers.co.uk/showproduct.php?prodid=MB-280-GI&tool=5) and the board has CrossFire support apparently.

It has two PCI-E x16 slots, so will I still be able to efficiently run two 5870s? I've just ordered one of the cards, but I want to upgrade to another one in the future. Will the speed double (or almost double) or will it not increase by as much since it will be using an x16 (x4) slot?

[Clavulanic]

From what I understand the bandwidth is a non-issue for mining. For gaming it is much more important. People have modified PCIE x1 slots to run 5870's and reported no loss or almost no loss of speed. You're speed should double.

I have the same situation, a x16 and x4 2 slot mobo on the way with 2 5850's so we'll see.

[dikidera]

May i join the club with 2xPCI-E x16 slots with one in x4 mode? 

I will also soon be ordering another 5850 to CF.

[keybaud]

I have 3 x identical 5870s, one is at 16x, one at 8x and one at 4x, they all run at the same hash rate.

Here's a rig using 4x HD5970 all on x1 slots (not bitcoin mining, but same idea):

http://blog.zorinaq.com/?e=42