How much performance am I loosing by using a second slot?

[Nocturn]

So, I decided to finally update from x299 to z790, but the MB I got turned out to be  broken, so while I waiting for the other mb to arrive, I wanted to find out, how much of the performance of my 4090 am I loosing by using the second pcie slot? 

[KnoT]

Get GPU-Z and check the PCI-E speed/lanes.

[RONOTHAN##]

Depends on the board you've got. If it's one that has x8/x8 support so you and are running at PCIe Gen 4x8, then it's somewhere in the neighborhood of 5%, upwards of 10% depending on the exact game. If it's not a board with x8/x8 support (most don't), then it's more like 10% on average, upwards of 30% depending on the game and resolution you're playing at (some games don't care, while others care a ton). 

[Nocturn]

9 minutes ago, RONOTHAN## said:

Depends on the board you've got. If it's one that has x8/x8 support so you and are running at PCIe Gen 4x8, then it's somewhere in the neighborhood of 5%, upwards of 10% depending on the exact game. If it's not a board with x8/x8 support (most don't), then it's more like 10% on average, upwards of 30% depending on the game and resolution you're playing at (some games don't care, while others care a ton). 

It says its running at x1 pcie 3. Is this even possible?

[Godlygamer23]

Just now, Nocturn said:

Is this even possible?

What specific motherboard are you using?

[Nocturn]

Just now, Godlygamer23 said:

What specific motherboard are you using?

Gigabyte Z790 Aorus Master

[Godlygamer23]

1 minute ago, Nocturn said:

Gigabyte Z790 Aorus Master

Which slot are you actually using? 

[Godlygamer23]

4 minutes ago, Nocturn said:

Gigabyte Z790 Aorus Master

The second slot appears to be wired for PCIe 3.0 x1, and the last slot is wired for PCIe 3.0 x4. 

[RONOTHAN##]

7 minutes ago, Nocturn said:

It says its running at x1 pcie 3. Is this even possible?

Are you running it in the 2nd from bottom PCIe slot? That's the only slot on that board that runs at x1 PCIe, and it only runs at Gen 3 (same with the x4 slot). 

 

You're giving up a ton of performance by not being in the top PCIe slot with that board (the 2nd gen 3x4 slot is equivalent to running at x16 Gen 1.1):

https://www.techpowerup.com/review/nvidia-geforce-rtx-4090-pci-express-scaling/28.html

 

Being at x1 is no where near enough bandwidth to run that GPU properly. You want to at least be in the bottom PCIe slot, though the top slot is really the only one that properly gives the 4090 the bandwidth it needs. 

Edited July 16, 2023 by RONOTHAN##
mixed up the slot order of which is x4 and which is x1