Thank you but I was specifically asking about Gen 3.0 x4 vs x16. (Deskmini x300/RX 6650XT)My tests are from testing in Timespy with the b660i board and comparing m.2->Oculink performance with x16 performance baselines, where I had some results within margin of error. However there are a few tests done by other sites which are good starting points also:
General observations:
1) Lower tier (slower) cards benefit less from more pci bandwidth
2) The higher the resolution (the lower the FPS) the less impact of bandwidth
Scaling for 5700xt:
With a weaker card (up to ~RTX 2080) there is potentially less than 1% loss between Gen 3.0 x8/x16PCIe 4.0 and PCIe 3.0 - Difference between x8 and x16 with the fastest cards - Where does the bottleneck begin? | Page 7 | igor´sLAB
Especially after the tests of the B550 motherboards, the justified question about the problem with the split PCIe 4.0 ports naturally arises. PCIe 4.0 with 16 or 8x connection should not show any…www.igorslab.de
Scaling for a 3080:
4.0x4 and 3.0x8 within ~4% of Gen 4.0x16 and within ~3% of Gen 3.0x16.NVIDIA GeForce RTX 3080 PCI-Express Scaling
NVIDIA Ampere finally brings PCI-Express 4.0 support to the high-end graphics market. The new interface promises twice the bandwidth of PCI-Express 3.0. We've setup an AMD Ryzen 3900XT system to test how various PCIe generations and lane widths affect gaming performance.www.techpowerup.com
Scaling for a 4090:
Here we have 4.0x4 and 3.0x8 within ~6% of 4.0x16.GeForce RTX 4090 and Core i9-13900K PCIe scaling test shows 2% difference between x16 and x8 mode | igor´sLAB
PCI Express (PCIe) is the standard interface for connecting devices within a computer, and the fourth generation of this standard, PCIe Gen4, offers significantly faster speeds and much greater…www.igorslab.de