2xGPUs & PCIe lanes

Any advice please? I can't seem to find this in the config guide.
If I have two identical GPUs (1080Tis in this case) how would Resolve be if one were installed on a 16x PCie bus, the other on a 16x (electrical 4x)? Would likely set that up as one GPU only for the displays, the other for compute only & the first also as 'use display for compute'. Any downside to Resolve performance benefits with that config?
I 'could' move things around to accomodate 2 x identical 16x PCIe buses, but presently I have a thunderbolt card installed which requires the use of one particular PCie slot, hence the limitations.
Thanks.
If I have two identical GPUs (1080Tis in this case) how would Resolve be if one were installed on a 16x PCie bus, the other on a 16x (electrical 4x)? Would likely set that up as one GPU only for the displays, the other for compute only & the first also as 'use display for compute'. Any downside to Resolve performance benefits with that config?
I 'could' move things around to accomodate 2 x identical 16x PCIe buses, but presently I have a thunderbolt card installed which requires the use of one particular PCie slot, hence the limitations.
Thanks.