I was spending a bit of time just looking at hardware on the internet, wishing for this and that, and feeling all excited about stuff I probably won’t be buying any time soon. But in one of those dreams where I build myself a super rendering pc, I started to wonder if motherboards with four pcie 16x slots are really worth the money. I have seen lots of motherboards with three or four pcie slots for less than half the cash, and the only difference is the speed of the pcie slots (they are obviously slower). How does this affect blender render times? Anybody know for sure? How critical is the pcie slot speed? What would the minimum speed for a pcie slot be for a good performance?
I guess that for rendering animations and stills the pcie bus speed is not too critical, but I honestly do not know.
Note: When I say “expensive MB”, I really mean “higher-spec” versus “lower-spec”, and not higher vs lower quality.
It is not critical, when the scene is uploaded to the GPU memory the PCIe bus is idle more or less.
PCIe 2.0 x4 make 2 GB per second, you need only a few seconds to fill you GPU memory.
Does not affect render time at all.
Personal I would not go < x4 but x1 schould work too.
pcie slot are not only different the speed. they are different sizes. a pcie 1 slot is about an inch and a half long, a pcie 16 is about 5 inches long. there is no way you are going to fit a good graphics card in a pcie 1 slot. for every graphics card you are going to need a pcie16 slot, and there are performance cards that require 2 slots for a single card, usually for custom cooling solutions.
a pcie1 is what regular pci is on old pcs while pcie 16 is like the agp slot. there are things not even your biggest hammer can fix.
Well, there are PCI-E 16 slots that only run at 4x speed.
And it is possible to run a PCI-E 16 graphics card from a PCI-E 1 slot by using a cable, as I did (for non-Blender purposes) about year until it was no longer profitable. Not saying it should be done, but it can be done. You’re on your own when it comes to mounting the cards, though.
Thank you, as I thought. After reading your posts and seeing many benchmarks on the net, you must really need the little bit extra to pay such a large difference in price. I quite like the asrock 990fx extreme3 for example, that costs half of the asrock 990fx extreme9. The only difference appears to be silly little things like an extra pcie slot, pcie slot speed, and other things that I don’t mind about. Wouldn’t it be nice to fit three gpus in that eh? Someday…
Cheers!