Motherboard with Multiple PCIe Slots

[boyburger17]

Hi everyone, I building a budget rig and need some advice for my motherboard.  Right now, I am only looking to buy one GPU and then maybe add another down the road, so I would like a mobo that I can expand on.  I have seen on sites like newegg.com that there are some cheap mobo's with multiple PCIe slots, but they say things like "2(x16, x4)". 

Does this mean that if I run two GPUs the second will get only a quarter of the power as the first?  How will this affect my mhashes?

Thanks!

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[TheBigYak]

The general consensus I believe is that you don't need a full-width PCI-Express bus to get the most out of the cards.  I know I've seen plenty of people running at x8 with no problem.  The only thing you've got to be concerned about is connectivity, you may need an x4 to x16 riser to allow them to connect.

[grottenolm]

That's right. At least from my experiments with FirePro W7000/5000/4800 cards, it doesn't matter AT ALL if I run them in x16, x8 or x4 slots. Also no impact if I chose Gen3, Gen2 or Gen1. All have the same hash rate in cgminer.

Technically: to my understanding bitcoin mining needs very little info to be pushed to the graphics cards, and then huge calculations are done on this data. The final result is also tiny, so there is very little traffic going in and out.

Those x16 Gen3 Slots are meant to transfer lots of data to/from memory, which seems not relevant here.

[boyburger17]

Ok, perfect.  Thanks guys!

[Splicer]

That's good to know, so basically any cheap mobo w/ pci express slot for a fast card is all that is really needed. Beautiful!