[SOLVED] GPU impact if installing M.2 SSD in bottom PCIe x16 expansion slot?

[BlueScream]

Currently running the boot disk from the only M.2 slot provided on my Asrock 390 Phantom Gaming 4S Mobo. Wish to add another M.2 SSD via adapter in the bottom PCIe x16 expansion slot , the GPU of course occupies the top PCIe x16 slot. The Mobo manual spec states: "2 x PCI Express 3.0 x16 Slots (PCIE1/PCIE3: single at x16 (PCIE1); dual at x16 (PCIE1) / x4 (PCIE3))" My research suggests that installing the SSD in the bottom PCIe x16 slot may cause the GPU to switch from x16 (PCIE1) to x4 (PCIE3) since the two slots share the same pipeline. Since x16 (PCIE1) and x4 (PCIE3) have equivalent throughput (4.0 and 3.94 GB/sec respectively), the impact on GPU performance should be minor. Do I have this correct? Is there any other considerations I may be missing?

 

[BlueScream]

Forgot to mention the Mobo manual states the PCIe x16 slots support NVME SSD as boot disks, although I will only be adding additional storage, the boot disk will remain in the M.2 slot.

 

[hotaru.hino]

The "PCIE1/PCIE3" isn't referring to the version, it's referring to the slot name.

 

[BlueScream]

The "PCIE1/PCIE3" isn't referring to the version, it's referring to the slot name.

Thanks but I am not sure how your response relates to my question. I will admit I am struggling to understand the tech language but doesn't "PCIE1/PCIE3" mean the slot supports both PCIE versions 1 and 3? Doesn't "single at x16 (PCIE1)" mean a single GPU installed operates on 16 pipes using PCIE version 1? And doesn't "x4 (PCIE3)" mean the slot supports components like an M.2 SSD via 4 pipes using PCIE version 3? If I am correct, the question is really whether installing a NVME SSD in the bottom x16 open slot will significantly impact GPU performance, assuming the two x16 slots share the same bandwidth. My research suggests it will not, but I cannot find a definitive answer after much research and so am coming to this forum, having followed Tom's Hardware for years.

 

[hotaru.hino]

Thanks but I am not sure how your response relates to my question. I will admit I am struggling to understand the tech language but doesn't "PCIE1/PCIE3" mean the slot supports both PCIE versions 1 and 3? Doesn't "single at x16 (PCIE1)" mean a single GPU installed operates on 16 pipes using PCIE version 1? And doesn't "x4 (PCIE3)" mean the slot supports components like an M.2 SSD via 4 pipes using PCIE version 3? If I am correct, the question is really whether installing a NVME SSD in the bottom x16 open slot will significantly impact GPU performance, assuming the two x16 slots share the same bandwidth. My research suggests it will not, but I cannot find a definitive answer after much research and so am coming to this forum, having followed Tom's Hardware for years.

What I'm saying is the terms "PCEI1" and "PCIE3" are the slot names, not the PCIE version. Both slots are PCIe 3.0.

It would be very suspicious for someone to sell an upper midrange board with a PCIe 1.x slot for the video card in 2019.

 

[BlueScream]

Thank you for providing further clarification. Good to know my GeForce 2080 Super is running on PCIe 3.0.

Do you know whether the two PCIe x16 slots share the same pipeline, and if so, weather installation of an SSD in the bottom slot will significantly impact GPU performance?

 

[hotaru.hino]

Thank you for providing further clarification. Good to know my GeForce 2080 Super is running on PCIe 3.0.

Do you know whether the two PCIe x16 slots share the same pipeline, and if so, weather installation of an SSD in the bottom slot will significantly impact GPU performance?

https://www.techpowerup.com/review/nvidia-geforce-rtx-3080-pci-express-scaling/27.html

An RTX 3080 doesn't see more than a 10% performance drop unless you put it into a PCIe 1.x x16 slot. So no.

 

[SkyNetRising]

Do you know whether the two PCIe x16 slots share the same pipeline, and if so, weather installation of an SSD in the bottom slot will significantly impact GPU performance?

PCIE3 slot doesn't impact operation of PCIE1 slot.
PCIE1 runs at x16 mode.
PCIE3 runs at x4 mode.

 

[KyaraM]

I would just use a SATA SSD, honestly. For a data drive, that's plenty fast and much less of a hassle.

That said, I had to run a GPU in the x4 slot of my old system's mainboard for a long time, which runs on x4 by default, and never noticed much of a difference in performance. Not even when putting the card in my new system temporarily until I got my 3070Ti. Average FPS were pretty much the same most of the time, and the one situation when I did notice a difference, I could attribute it to the processor (lots of things to load). Not sure what card you use; the one I have made that experience with is a 1070, so a bit older already and it might be different with newer cards; but it should be fine I think even if you go that route. You would have to test it yourself, though.

 

[BlueScream]

Many thanks for all responses provided!