RavyuS

Hi, I am interested in trying a 8 GPU VM setup with an i9-7980xe running 8 VMs with GPU passthrough. Unfortunately, none of the X299 boards have more than 4 PCIex16 slots, making this impossible without any external setup. I stumbled upon this PCIe Splitter/Riser by SuperMicro and thought it could work. My only question is, are the two GPUs attached to one PCIe x16 slot going to give issues in IOMMU splitting, using ACS Override? I'm not sure how the chipset/mobo is going to recognise this setup. I'm fine if the GPUs run at x8 capacity as I'm not looking at very high-end gaming. Just need a single board 8 VM solution. Edit: I did a little bit of research. Apparently I need to look out for PCIe Bifurcation support on motherboards in order for this to work. Assuming I can find one, will IOMMU grouping still be an issue? Thanks! Ravyu

Oh, that is interesting. I skipped over the idea that the motherboard could be doing some extension of sorts. I can't seem to find a way to disable this in my motherboard UEFI/BIOS. I want to try a 1x8/2x4 setup and see if there's some improvement, but the mobo settings are disgustingly basic. Yup, I've tried this and can confirm VMs using the slot 3 GPU artifact heavily. I've only ran Unigine Benchmarks on them so far, and that isn't particularly heavy on CPU so 1c/2t should suffice for each VM at the moment. Besides, I ran 2 VMs using 1c/2t and they worked flawlessly!

Hi, I'm currently testing a Triple Gaming VM set-up on my unRAID server 6. This is my current config- CPU: i7-7700k Stock Motherboard: Gigabyte Z270X-UD3 GPUs: GTX 750ti (Slot 1), 2x GTX 1070s (slot 2 and 3) PSU: Corsair RM750 (750W) So, I managed to run 3 VMs, with each VM taking 1c/2t from the CPU, with 1 GPU passed through to each. I tested Unigine simultaneously and was pretty impressed with the results, except for the VM running with the GTX 1070 in slot 3. That one was giving serious artifacting (both in-game and desktop) and I wondered if it was an issue of lack of lanes from the CPU. The i7 only has 16 lanes, so I assumed it would be a 1x8/2x4 setup. But that wouldn't make sense since the other two VMs were running flawlessly. I used GPU-Z to check the lane distribution, only to find this. Turns out, it was 2x8/1x4, with the first 2 GPUs using 8 lanes. I understand that the motherboard specifies x8 to the first two slots, and x4 to the last slot, but I'm clueless as to how this would work when the flagship CPU only has 16 lanes for PCIe. Curiously, if I swapped the GTX 1070 in Slot 3 with any of the other two GPUs, the VM would artifact too heavily for normal use. Just swapping the 1070s yield this problem as well. Any thoughts? Thanks!