PCIe x4 (in x8) clarification

[a.dresner]

Hi

Can someone help me understand what PCIe 4.0 x4 (IN x8) Slot means?

I have a https://www.supermicro.com/manuals/motherboard/X12/MNL-2367.pdf X12STH-F/LN4F

It has 3 slots:

• 1 PCIe 3.0 x4 (in x8 slot),
• 1 PCIe 4.0 x16,
• 1 PCIe 4.0 x4 (in x8 slot)

I want to put both an HBA 9207-8i (x8) and AOC-SHG3-4M2P (x8)

I have the feeling one of the two cards will have half the lanes it can support? X4 in x8 slot means its x4 lanes/speed but the slot is x8 size?

Cheers!

 

[Samuel Tai]

You guessed correctly. That motherboard has an Intel C256 chipset. The chipset only has 24 lanes, so this is divided between the 3x slots as listed. 16 lanes to the x16 slot, and then 4 lanes each to the 2x x8 slots. You may want to put the AOC-SHG3-4M2P on the x16 slot, and the HBA on a x8 slot.