3070 and pcie lanes. 8 vs 16. Performance difference?

[iameatingjam]

So I don't know why but my gigabyte vision oc 3070 only runs on 8 pcie gen 4 lanes. A couple months ago I went to great lengths to diagnose the problem but never found a solution. I had two m.2 drives ( and no other pcie devices). I tried disconnecting the secondary one. then I tried moving the primary to to the secondary slot, running gpu load at 100% but still 8x. Yes gpu is in the top slot, yes I tried I reseating many times, tried cleaning the connectors and everything. I eventually ended up giving up.

But now I'm wondering, what exactly would the performance difference be? There's a lot of threads about gen 3 8 vs 16 but not so much gen 4. I have a 1440p monitor but sometimes I render at 4k if AA isn't very good. Would the difference be negligible?

BTW I have an 11600kf and my motherboard is gigabyte b560 ds3h but its a weird 'ac-y1' model that I can't find any updates for. Wish I had a spare motherboard or gpu to do some troubleshooting with, but I don't.

Also I should be okay to add a third m.2 through a pcie adapter, right? because that would go through the chipset.... right?

 

[joemama]

There shouldn't be much difference, you can check the PCIE scaling with a 3080 tested here: https://www.techpowerup.com/review/nvidia-geforce-rtx-3080-pci-express-scaling/26.html
Since PCIE4.0 has twice the bandwidth of 3.0, you can interpret the results of 3.0 16x as 4.0 8x

 

[sLowEnd]

But now I'm wondering, what exactly would the performance difference be? There's a lot of threads about gen 3 8 vs 16 but not so much gen 4. I have a 1440p monitor but sometimes I render at 4k if AA isn't very good. Would the difference be negligible?

Yes, it's negligible. PCI-E 4.0 x8 has as much bandwidth as PCI-E 3.0 x16.