Cycles CUDA rendering with PCIe splitter?

Hey everybody,

I am looking into purchasing a PCIe splitter so that I can use more GPUs than my motherboard can handle for high resolution 3D image rendering with CUDA. My question is, will Blender recognize my GPU array if it is plugged in via a PCIe x4 slot? I could also plug it into a PCIe x16 slot, but it is still a x4 connection. I am unsure of whether the GPUs will show up as useable under CUDA, or if Blender has a limit on the maximum number of GPUs. Perhaps someone has experience with this and could enlighten me.

This is the splitter I am looking to get. I eventually want to work my way up to 8 or even 16 GPUs so that I can render single frames dramatically faster. This cluster was released in August, so I don’t expect anybody to have experience with it.

This splitter is from the same company and has been around for a while, so perhaps someone here has used it and could tell me about their experience with it.

Thank you for reading.

Yeah, for rendering something like that would be fine :slight_smile:

A single PCIe 2.0 x1 Lane provides 500 MB/s of bandwidth, so even if your using 4 x 4GB cards, it would take a maximum of 8 seconds to fill them all up :slight_smile: That would be fairly inconsequential compared to the BVH build time on complex scenes, and the render time as well.

Thanks, zeealpal. I actually contacted the support team at amfeltec to ask them the same question, and they told me they’d download blender and test it for me. If anybody is interested I’ll post the results here.

Yes this looks quite interesting, please post the results!
It’s not quite clear from the description, are the PCI-E slots on their splitter powered? As far as I know GPUs can draw some watts from the slot even when there’s enough power provided by 6/8-pin connectors, and drawing potentially 4x75W from a budget motherboard would be a really bad idea.

is there news from amfeltec for result render under cluster?
I’m very interesting :evilgrin:

Hello, sorry for the delay.
Amfeltec did get back to me with their results, and the cluster worked with Blender with no problems. They were using a combination of different GPUs (GTX 4xx, 6xx, and 7xx I believe) and Blender was able to use all three for CUDA. Anton, to answer your question, no the GPU will not draw the necessary power from the PCIe slot. You need to have an external power supply wired up. Amfeltec has detailed instructions on wiring up the power and control signals for their cluster.

i’m sorry for the DELAY…
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