CPU impact on a GPU server

[smearballs]

I'm thinking of buying one of these GPU servers for Octane rendering and trying to configure a machine with the best bang for the buck.

https://www.mediaworkstations.net/product/gpux/

I'm wondering how much CPU power affects performance on a rig like this. Does it matter which chip I would get on this machine, or how many cores the server has since octane is using exclusively the GPUs?

Same question goes for Ram -- is there a certain amount of ram and CPU power that would be redundant on a GPU server like this when it comes to Octane rendering?

Anyone have experience with a server like this or a recommendation on configuration would be greatly appreciated.

[smicha]

32gb of RAM is recommended. CPUs get v4 e5 series . See my build on 14 GPUs her on the forum

[Terryvfx]

smicha can you please elaborate a bit more on why this numbers makes sense? I've also been wondering the need for an expensive GPU and a lot of ram on a setup that would only use GPUs, I do understand that you need a CPU capable of handling the amount of PCI-e lanes required for all the cards to be active but beyond that I don't know.

[smearballs]

Indeed, that's my biggest question. Cpu price on a system like this can vary by thousands of dollars. Wondering what grade of Cpu would be capable of operating 8 or more GPUS efficiently. There must be a threshold for a sufficient chip where price point and performance max out.

[smicha]

smicha can you please elaborate a bit more on why this numbers makes sense? I've also been wondering the need for an expensive GPU and a lot of ram on a setup that would only use GPUs, I do understand that you need a CPU capable of handling the amount of PCI-e lanes required for all the cards to be active but beyond that I don't know.

RAM usually you should have 2x more than VRAM, so for titan X is goes to 24GB of RAM. But if your scene exceeds that and you'd want to have textures over the core (loaded into RAM) you'll need more RAM. 16GB setup shall work too, so you may save 100$ and go with a single 16GB ECC stick

What is the cost of the case you want to buy? If you want to go as cheap as possible 2603v4 is an option, or 1620v4.

14gpus...
viewtopic.php?f=11&t=58045

[glimpse]

Indeed, that's my biggest question. Cpu price on a system like this can vary by thousands of dollars. Wondering what grade of Cpu would be capable of operating 8 or more GPUS efficiently. There must be a threshold for a sufficient chip where price point and performance max out.

You would not get any benefit in Octane from anything more than good quad core ;) the problem is You might not be able to run more GPUs due to issues with motherboards for those quad cores.

[rappet]

Indeed, that's my biggest question. Cpu price on a system like this can vary by thousands of dollars. Wondering what grade of Cpu would be capable of operating 8 or more GPUS efficiently. There must be a threshold for a sufficient chip where price point and performance max out.

You would not get any benefit in Octane from anything more than good quad core the problem is You might not be able to run more GPUs due to issues with motherboards for those quad cores.

Hey Glimpse,
But when loading scenes into Octane all cores are in progress, so 28 cores (dual xeons 14 cores) must be much faster then i7 quad or hexa core doing this particulary Octanejob, no?
Maybe KonstantinosD can help us out here?
@KonstantinosD, if it not too much to ask, it would be great if you could test the difference between the dual xeon and the i7 in loading a heavy and complex Octane scene
cheers,