Have the same "problem" with my Radeon VII, In bios it run´s in x4, and have a Threadripper 2950x and a ASUS ROG X399 motherboard, so plenty of PCI lanes, but it botherd the living hell out of me......diden´t matter that it totaly smashed cards that cost $6000-$10000 in a few benchmarks, it was that a GTX 1050 was faster Direct 2D........it was only then i bought a RTX 2060 and that showed x16 in BIOS but it was then i started to do some work with it CAD, IFC export and imports to Revit and BIM modeling I noticed how incredible slow thought it was, hade to turn down texture quality so the BIM model looed like it was built in Lego, so I went back to my Radeon VII even if it showed x4 in BIOS but I can work with DWG files that are around 4-500 MB and it don´t even lag, and now it´s AutoCAD the 1core champion and they still realeases a new version every year, had to check the system recommendations, AutoCAD 2021 had support for muliple processors did they had to add that becouse of all of the weird chipsets with dual Xeon´s and DDR 3 and M2, becouse i´m pretty sure that a Pentium 4 will do just fine for the 64 bit and Pentum 3 for 32 bit ;-)
But be aware regarding the graphics cards I think they have had 1 consumer card that has been "certifed" to run AutoCAD and it was a Geforce MX150, but not for 2021......there you can choose any thing ATI/AMD and Nvidia has released as "Pro" card so it´s from old ATI fireGL´s that the lower speced ones you probebly would find in a electroncs recycle basket to RTX 8000 whitch cost the same as a decent house in Tanzania or what you get for around $8000 and I saw in the same shop sold Quadro P5000 to the bargin price of $2500 but some shop´s still sell Quadro M card´s .but they diden´t sell any GTX 1070.....weird...
Yeah after that detour i think i have to circle back to that BIOS showed the wrong PCI x4 then should have been x16....so i think you can drop it even if seems to have the same OCD I tried everything even scrubbing the PCIE slot with a tooth brush and ethanol, bought a riser cable and eventually a new card, Iknow that Radeon VII don´t use all 16 lanes at all time and probebly most others card to.
How it can happen....who knows ,maybe so easy that the x4 value got stuck in some part of the memory after maybe a crash or a Hard power off......my started at x8 and see and feel the differens between x8 and x16 isn´t that easy.........so then i dropped down too x4 it felt good.....couse then we are down to PCIE 1 x16 and thoose cards can´t do 100 fps in 4K
/Kingtompa