Crossfire compatiblity

[Trueno07]

I've been researching parts for a few months now, and i can't for the life of me figure out how to tell (100%) if a motherboard is crossfire compatible.

I've read guides and the ATI web page about cross fire compatible motherboards, but there seem to be only a few there, and several on newegg that are listed as 'Crossfirex compatible'.

I'm currently looking at this motherboard:

http://www.newegg.com/Product/Product.aspx?Item=N82E16813131404

First off, can someone explain to me what:

"1 x PCIe 2.0 x16 (single at x16)
1 x PCI Express 2.0 x16 slots (@x4 mode, 2.5GT/s)"

means in terms of crossfire? (for say, 2 5770's)

I've seen people mention different types of crossfires (8x8, 16x8, i have no idea) and it's kinda the one bit of knowledge I'm lacking when it comes to computers. Could someone explain or link me to an explanation? (Wikipedia was no help from what i remember)

Thanks for any help ya'll have to offer,

Trueno07

 

[saint19]

Hi, means that in Crossfire mode, your GPUs only can run @x4.

 

[snurp85]

Basically the socket you are looking at is limited to 16 threads devoted to the graphics card on the motherboard. so if you will notice on all of the motherboards with socket 1156, they will have one PCIe v2.0 slot at 16x and some will have a second that has either a PCIe v2.0 4x or 8x slot. I would chose one with a second slot capable of running at 8x.

What all of this means is what "saint19" said above, when running a second card in crossfire, it will run at either 4x or 8x. In the case of boards that run 8x, your primary card will also run at 8x. Tomshardware has done an article recently about the effects of running crossfire at 8x8x instead of 16x16x and showed that there was negligible difference between the two under most conditions.

oh and the "x" is basically referring to the bandwidth of the slot.

 

[Trueno07]

Best answer selected by Trueno07.

 

[Trueno07]

Thank you snurp85 that makes much more sense!