Does running a 24gb GPU on pcle5.0 x8 slot impact the performance vs running it at pcle5.0 x16

[Bihaidi]

Does running a 24gb GPU on pcle5.0 x8 slot impact the performance vs running it at pcle5.0 x16, I am currently trying to choose a mobo for my build and looking at the ASUS ROG STRIX X670E-E GAMING WIFI, that board has 4 m,2 slots (3 are pcle5.0 running from the CPU, the last one is a pcle4.0 from the chipset) now then if I were to populate all 3 m.2 keys with pcle5.0 slots that would leave about 12/24 lanes leftover meaning 8 usable lanes at pcle5.0 for the gpu, that got me curious about how the number of lanes would impacts the performance for context the pcle5.0 bandwidth is 63 gb at 16 lanes and 32 gb at 8 lanes, and since most modern GPU'S dont really go above 24gb it should technically run the same, but I am fairly new to building computers so don't really know and would appreciate if anyone could kindly leave a comment below with the answer.

[Ralf]

The only PCIe 5.0 gpu out there is the Nvidia H100 PCIe with 80GB HBM2e.

[Kilrah]

I.e. your GPU will be running at PCIe4 x8.

Check if someone did performance comparison at PCIe4 x8 / x16 with the GPU you're after.

VRAM amount doesn't matter.

[Sauron]

16 minutes ago, Bihaidi said:

bandwidth is 63 gb at 16 lanes and 32 gb at 8 lanes, and since most modern GPU'S dont really go above 24gb it should technically run the same

This is not how it works. Even if they had 1TB of vram it wouldn't automatically mean they could saturate pcie 5 16x bandwidth. As mentioned there aren't even any consumer GPUs using PCIE 5 yet, however it's unlikely any current GPU would saturate even a 4.0 x8 slot. As you can see there is barely any difference between 4.0 16x and 3.0 16x which is equivalent to 4.0 8x:

 

 

In fact 2.0 is still fine, which has the equivalent bandwidth of 5.0 2x.

[jaslion]

45 minutes ago, Sauron said:

This is not how it works. Even if they had 1TB of vram it wouldn't automatically mean they could saturate pcie 5 16x bandwidth. As mentioned there aren't even any consumer GPUs using PCIE 5 yet, however it's unlikely any current GPU would saturate even a 4.0 x8 slot. As you can see there is barely any difference between 4.0 16x and 3.0 16x which is equivalent to 4.0 8x:

 

 

In fact 2.0 is still fine, which has the equivalent bandwidth of 5.0 2x.

It does vary depending on the game but a 3.0x16 link is basically fine for all

[ewitte]

3 hours ago, Kilrah said:

I.e. your GPU will be running at PCIe4 x8.

Check if someone did performance comparison at PCIe4 x8 / x16 with the GPU you're after.

VRAM amount doesn't matter.

I've seen cards with insufficient VRAM getting hit harder by PCI bandwidth.