Confusion about CPU lanes

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Hello,
I’m lucky to have gotten my hands on a 9800X3D while they were in stock, and I’m planning a build around the Gigabyte X870E Aorus Elite Wifi7.
This is my first new build in about seven years, so I’m a bit behind the curve and I was hoping to get some advice, specifically about the board’s lanes.
I understand that not every PCIe/SATA/NVMe slot can be populated simultaneously, and that plugging a device into a slot will disable or reduce the bandwidth to other slots. While I have block diagrams of the board in the user manual, I’m confused about which slots can be used and in what order. Is there a way to find this out so that I can maximize the number of devices I can use? I’m a bit of a data hoarder and I have a lot of drives, so I really want to be strategic in how I go about this.
Ideally I want to populate as many NVMe and SATA slots as possible, and I’ll likely be using an extra SATA expansion card in the 4x slot.
As I understand it, populating all of the NVMe slots won’t be possible, and I can’t touch the 8x without impacting GPU performance.
Thanks for any advice.

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Hello,
I have the exact same board that you’re referencing and it goes like that:

  • PCIEX16 is for your main card (16 lanes) and will share pcie lanes with the M.2 slots at M2B_CPU and M2C_CPU thus if you don’t want to slow down your graphics, don’t populate those 2 slots.
  • PCIEX4_1 (PCIE 4.0 at 1X) and PCIEX4_2 (PCIE 3.0 at 4X) are from the chipset and do not share lanes.
  • M2A_CPU (PCIE 5.0 at 4X) is from the CPU lanes and doesn’t share lanes.
  • M2D_SB (PCIE 4.0 at 4X) is from the chipset and doesn’t share lanes.
  • 4 x SATA ports 6 Gbps that doesn’t share lanes.

So a quick recap is that it gives you 2 x M.2 NVME and 4 x SATA ports that you can use without impacting anything else in your system.

Hope this helps.

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Thanks so much for your reply, this is exactly what I needed. I should be able to use this information to plan out where I want all my drives.
Much appreciated!

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you can find this info in the mobo manual for future reference

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Since mobo manuals aren’t written by non-native-speaking English-Chinese persons, I have trouble understanding the technical aspects of motherboard manuals. I am pretty sure @Dansrage and others have the same problem as I do.

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It is extraordinarily unlikely that dropping the slot to 8x will bottleneck your GPU. If you can leave those slots open, sure, but if you need more NVME storage I wouldn’t feel bad about using them.

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It is kind of a shame to have four M.2 slots and only to be able to use two. That said, I only have two M.2 drives right now, so it’s not a problem.
I’ve heard conflicting things about the 16x slot, some people say that dropping it to 8x it has no impact on the GPU, some people say there’s a small impact of like 3-5% performance. I have a 4070 Super, so it’s not the highest-end card.

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A ~3% drop in game frame rates at certain settings is a common response to a bandwidth divide by two in PCIe scaling benches on GPUs. I don’t know of any recent scaling data for GPGPU.

Lower end GPUs usually aren’t x16 anyways. The 7600 (XT) and 4060 (Ti) are 4.0 x8.

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