Bitcoin Forum

I'm shopping for motherboards right now and it's hard to find boards with multiple PCIe 2.0 16x slots. Is this a factor? I'm thinking about getting 2 6990s.

get a asus 890fx.... one of the best boards on the market, plenty of options and usb 3.0. If you want to add more cards ge tthe extreme edition as it has more spaced out slots. Otherwise buy a basic board and use some extenders from cablesaurus.com who post on this forum.... top sellers!

For mining there is little if no difference between any PCI-E speed.

No need to worry about that.


Gaming takes a minor hit on 8x speeds, but that is all.

but would it make a difference in performance if I have a card in a 16x slot and one in a 8x slot?

nope you can use x1 for gpu's in mining... they take little bandwidth

Not unless you crossfire. If you crossfire both lanes will bump down to 8x, which should not be an issue for mining, but some have reported it to be.


Just put both in without a crossfire bridge and it will be fine.

Ah thanks for the reply guys. New question: I found a decent board with 2 16x PCI2.0, but speaking of crossfiring, is it a better idea to crossfire the two cards in the 16x slots?

I'm creating a thread here to help with just this sort of thing.
http://forum.bitcoin.org/index.php?topic=14182.0 (http://forum.bitcoin.org/index.php?topic=14182.0)

If you come up with a good find you can maybe add your motherboard to it ;)

Yes but only for gaming.  I hear that crossfiring lowers mining speeds even if in full speed slots, though I cannot confirm that personally.

No.  Most folks have found they actually get better performance running both cards as individual miners without crossfire than having one beefier miner with crossfire.

If it's a dedicated miner there are cheaper boards then that asus.  1x-16x doesn't matter.  There's no advantage in crossfire'n them for mining.  You may get the advantage of not dealing with dummy plugs tho.

Now if you were planning on using the machine or do more then just mine on it (either while it's mining or after it's retired from mining) then I can see an advantage in going higher.  There's the possibility of a higher resale value as well.

Yeah it'd be a dedicated miner. Now I'm thinking with going for 4 cards but I can't find any boards with 4 PIC-e slots that are under $170. Suggestions?

anyone know if any places like microcenter, the shack, etc carry pci extender cables or parts to make your own? don't want to wait on shipping.....