I just built a computer with the same issue.

The case was a Rosewill Thor v2 and the video card was an Asrock 5700XT(the one with the rgb on the middle fan, but not the Taichi one).

When you try to plug in the gpu, it'll start to insert into the pci port, except the back side of the video card was sliiiiiiightly too short. The part of the back on the gpu that turns 90 degrees so you can screw it to the back of the case to support the gpu hits the metal, so you can't push the gpu fully into the slot.

We're talking just a few millimeters, so it's one of those annoying things.

You can either grab some vice grips to straighten out the back metal piece on the gpu to allow it to insert into the pci slot, or you can grab a grinder to slice off the pieces of metal on the case that is hitting against the juuuuuust too short gpu backplate.

If you do the second thing, you need to ziptie the gpu to the other remaining pci openings after you pull a few more of the little coverings blocking the other openings.

What I did was charge another $50 and installed a vertical gpu holder and a pci extender. It allows the customer to see the rgb on the fan on the gpu better, and fixed the problem.

I didn't know whose fault it was that caused the problem. Either the case has a slightly too long metal box with all the pci outlets, or the gpu had a slightly too short backplate and/or turned the backplate 90 degrees slightly too early.

I just woke up, and my brain's not working yet, so sorry for the incoherent rambling.