Need Help Finding x8/x16 PCIe Compatible CPU + Motherboard


Hello all!

So I'm doing a build and have been having trouble finding a CPU/Motherboard combination which would work for my needs. So essentially I'm putting together a machine for the purpose of 4k livestreaming. For this I am looking to get a RTX 3060 so that we can take advantage of Nvidia's NVENC encoding (and not have all of our rendering load placed solely on the CPU). Additionally for our video-in I am getting a Blackmagic 8k Decklink Pro Capture Card.

Now for the dilemma: the 3060 requires a PCIe x16 slot, which is to be expected. However the Decklink Pro also requires a PCIe x8 slot. This means that we would need a CPU which supports at least 24 PCIe lanes, and a Motherboard with the respective compatible PCIe slots.

I have not yet been able to find a combination CPU/Motherboard which fits these requirements, which is very surprising to me. When looking through different motherboards the vast majority of them only support 1x16 PCIe slot and then one additional 1x4 slot through the chipset, even when looking at motherboards which support 24+ PCIe lane CPUs.

I would love some recommendations and/or advice. Thank you!


  • magarity
    magarity ✭✭✭✭
    First Anniversary 5 Up Votes First Comment First Answer

    Usually if you populate a card that wants 8x lanes in the second slot then both get 8x. You lose a very little performance from the 3060 if its slot is 8x.

    The one 16x or two 8x is a chipset thing. All current generation desktop PCs do this. You need Threadripper or Xeon to get dual 16x slots.

  • PowerSpec_MikeW
    PowerSpec_MikeW PowerSpec Engineer
    5 Insightfuls First Anniversary First Comment 5 Awesomes
    edited December 2022


    Shouldn't be a problem with an X570/X670/Z690/Z790 platform.

    As an example X570 board with a Vermeer CPU.

    CPU: 24 Lanes

    X570: 16 Lanes

    Reserve four for interconnectivity either way. 20+12 = 32. 16X for GPU, 8X for the capture card. Two x4 NVME drives. The chipset provides PCIe lanes in addition to the CPU.

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