Motherboards with only one PCIe 4.0 lane.

[Olivia]

The motherboard I am looking at getting for an upcoming build only has 1 PCIe 4.0 lane.

Altogether it has:
1x PCIe 4.0/ 3.0 x16 slot
1x PCIe 3.0 x16 slot, supports x4 speed 2
2x PCIe 3.0 x1 slots

Now my GPU will take the only PCIe 4.0 lane on that motherboard, so if I was to get a PCIe 4.0 M.2 SSD does that mean it would only be able to run at 3.0 speeds as the 4.0 lane would be used by the GPU?

I would use the top M.2 slot, that is the one linked to the CPU not the B550 chipset.

Does it work like that? or do the M.2 SSDs use different hidden lanes or are M.2 slots their own PCIe 4.0 lane or something?

[Bad 💀 Motha]

The slot is not 1x lane.
Slots come in sizes for cards such as X16 and X1, that's how many lanes the device will use. Unless it's SLI/CFX 2 WAY Config which will use 2x physical X16 slots but divide the lanes into X8/X8 for 2x gpu configs.

Gen3 nvme ssd is pcie 3.0 and would require 2 lanes. Gen 4 nvme ssd is pcie 4.0 and would require 4 lanes.

Gpu lanes come solely from lanes onboard the installed cpu. The rest of your lanes comes from your Chipset, such as B550 or X570

Unless you use a multi-GPU config you can't run out of lanes. Even with 2 or 3 nvme ssds if the board even supports that many, most only support 1x nvme M2 slot with the other being M2 sata speed only. Higher end boards however can support up to 2 or 3 nvme Gen3/Gen4 ssds. Intel atm does not support Gen4 at its full speeds due to lack of PCIE 4.0

[Spec_Ops_Ape]

Bad 💀 Motha님이 먼저 게시:

Gen3 nvme ssd is pcie 3.0 and would require 3 lanes. Gen 4 nvme ssd is pcie 4.0 and would require 4 lanes.

NVMe drives use 2 or 4 lanes, PCIe 3/4 is bandwidth.

[Bad 💀 Motha]

Sorry yes gen3 nvme is 2 lanes

It does matter which M2 slot you use also. You must read the motherboard online pdf manual to see what each available M2 slot supports, not all available M2 slots will support Gen4 NVME, unless it says so. And the top most M2 is not always the fastest one.

[Monk]

Honestly, if you are going to fork out for a pcie gen4 nvme drive, just spend an extra hundred bucks and get a better motherboard.

Though, for the vast majority of games, it will have zero effect until nvidia direct loading tech is introduced on a wide scale, even then, it will be questionable how much faster it will be as it still will be using random read, which I do not believe pcie4 nvme's have any real improvements on over gen 3.

[Bad 💀 Motha]

It was pricey, but I'm happy I did it.

ASUS X570-E was about 250$
Rocket 4 1tb Gen4 ssd, 200$
Rocket 4 2tb Gen4 ssd, 400$

[Monk]

Those prices aren't too bad actually, nvme prices have dropped quite a bit, I think my 1tb 970 evo was around £400 when they were new (and totally not worth it).