BlenderRookie

Thanks for this information. I assumed that's how that would work but it's great to have confirmation.

No one here is wanting to do anything like that. I am simply trying to understand how the PCIe lanes work and if splitting them to multiple GPUs via "bifurcation"(thanks krakkpott) is possible. I am under no illusion that a GPU needs more bandwidth. Ideally, I want to build a rendering machine for Blender with 8 GPUs each running at x2 4.0 speeds or 3.0 speeds. There are plenty of options for x1 speeds but I have tested GPU rendering at 3.0 speeds on a x1 to x16 riser and there is a little bit of a bottleneck. But the bottleneck is small enough that two lanes would solve the issue. Frames rates don't apply because each frame take many seconds or minutes. Everyone, thanks for your answers. They helped me understand the issue to a better degree.

That's pretty much what I figured. But I was hoping a 4.0 capable MB would be smart enough to I guess use the 4.0 bandwidth of the cpu to essentially mimic a doubling of the lanes when running at 3.0 speeds.

I have a question about PCIe lanes. Suppose you have a MB(ASUS Prime X570-Pro) with PCIe 4.0 and you have 20 PCIe 4.0 lanes on your CPU(Ryzen 3000 series). That MB has three PCIe 4.0 16X slots. If I installed two GPUs that's PCIe 4.0 capable in each of two slots, each card will essentially run at PCIe 4.0 8X speeds. So my question is this, since PCIe 4.0 is twice as fast as PCIe 3.0, does that mean if I install two PCIe 3.0 GPUs(one in each of the same 16X slots) will they both be running at full 3.0 16X speeds? I hope that makes sense.

Thanks for the information.

Thanks for the information, You all pretty much confirmed what I already thought. I hate to lose that number 3 sata port.

I have an AB350M Pro4 with a Ryzen 1600X. The MB can be found here. This MB has four SATA 3 ports and two M.2 slots. On page 41 of the Motherboard's Manual it says, "M2_2 and SATA3_3 share lanes. If either one of them is in use, the other one will be disabled". My question is, does this mean if I put an M.2 drive in that M2_2 slot, the SATA3_3 slot will then be disabled or does it mean that the system will only be able to access either the M2_2 or SATA3_3 at any given time as opposed to simultaneous access? Thanks for your help.