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PCIe NVME SSD only connects with PCIe 3.0 x2 instead of x8

Level 7
Hi all,

I own an Asus X570-E Mainboard and since both of my m.2 slots were already occupied, I was very tempted by an expansion slot solution by Western Digital:

I bought it and it immediately worked plug and play, but when I wanted to check the speeds, i was irritated:

The Drive only connects with PCIe 3.0 x2 and therefore loses speed rates (at least crystal disk info states so)

My setup is as follows:

PCIEX16_1 is taken by an Nvidia 3080ti

PCIEX_1 is still covered by the graphics card

PCIEX16_2 is kept empty due to proximity to the GPU fans

PCIEX1_2 is occupied by an USB 3.0 hub

PCIEX16_3 is taken by the new Western Digital SSD now

I have found no setting in the Bios that would cause the slot to be slower and in the Users Manual (excuse the screenshots in german) it's only stated that PCIEX16_02 and PCIEX16_03 share their bandwidth, which should not affect me since the _2 slot is empty.

Does anyone have an idea what is the problem here?


Level 10
Only thing I can think of is that you're being throttled by one of the other devices...??

Level 10
First, I'm not sure if you're wondering about PCIe 3.0 vs 4.0. So, just to get that out of the way up front, according to:

that's a PCIe 3.0 card.

Assuming the issue is with x2 vs x8, I don't know your exact motherboard model, but I grabbed a PDF of the manual for the X570-E Gaming and there's something on page 3-15 that looks odd:


According to that, slot 16_3 is set to X2 if something's in slot 1_3. But, unless I'm misreading something, I don't think there IS a slot 1_3. Maybe it's a typo and is referring to 16_3 (which makes very little sense) or 1_2 (which would apply to you)? But, regardless, if you're using the M_2 slot, I think it says it's going to change 16_3 to x4. I guess I'd recommend checking Onboard Devices in your BIOS and seeing if it's set to Auto or X2 for that slot.

Level 7
Try it in


to see if that makes a difference.

I have Highpoint card and that runs @ X8 in that slot.