hi i am looking to build a home lab server. and i am totally new to this field.

i am currently looking for two motherboard and i am curious their compatiablity with MULTI gpus support under one os (linux or ubuntu). which means i want to use their totally gpu power at one task, just like using one gpus.

my desired task is to use at least two nvidia rtx 4090 gpus at their full speed and bandwidth under one system. is that possible?

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  1. cheaper: Pro WS W790-ACE (https://www.asus.com/motherboards-components/motherboards/workstation/pro-ws-w790-ace/)
  2. expensive: Pro WS W790E-SAGE SE (https://www.asus.com/motherboards-components/motherboards/workstation/pro-ws-w790e-sage-se/techspec/)

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these two motherboards are similar except for the capablity of Expansion Slots, as my understanding and my usage, that would be the max capability gpus usage.

in here i will list the specs of 1. Pro WS W790-ACE (copy from website):

Expansion Slots:

Intel® Xeon™ W-3400 and W-2400 Series Processors5 x PCIe 5.0 x16 slot(s) (supports x16, x16, x16, x0/x8, x16/x8 modes)* Please check the PCIe bifurcation table on the support site (https://www.asus.com/support/FAQ/1037507/).- To ensure compatibility of the device installed, please refer to https://www.asus.com/support/ for the list of supportedperipherals.

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i asked gpt4 how many gpus i can use at the same time running at full bandwidth under ons system.

i got this:

Second Motherboard:

With either an Intel® Xeon® W-3400 or W-2400 Series Processor, it provides 5 PCIe 5.0 x16 slots. However, when all slots are populated, the configuration becomes x16/x16/x16/x8/x8. This means you can run three RTX 4090 GPUs at full PCIe 4.0 x16 bandwidth, and if you install a fourth GPU, it will run at x8 bandwidth, which is not the full bandwidth for a 4090 GPU.

is that correct and concise in the real case?

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my questions is about the multi GPUs supports. as a person, i dont have money to buy a100/h100. i want to use multi 4090 as my workload and thats enough for me.

is this gpt4 answer correct? and can i achieve using multi 4090s with this motherboard?

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thank you guys soo much.

  • msaladBEnglish
    1·
    1 year ago

    Chatgpt is correct here if you use an Intel w-2400 CPU, which has 64 pcie gen5 lanes, but if you use an Intel w-3400 CPU you get 112 gen5 lanes. If you’re just running pcie gen4, you might get more lanes but I’m not sure.

    That said, if you’re just looking to run your gpus at full bandwidth and don’t need pcie gen5, you could go threadripper pro 3000 or 5000 series and a wrx80 motherboard for 128 pcie gen4 lanes.

    Also the new threadripper and threadripper pro 7000 series is coming out on Nov21. Personally I’d get that over the Intel w-2400/3400 series.