I just ran across a really weird hardware got ya.
I built my PC around christmas.
Here's the full specs, but the important part here is that it's an ROG STRIX B450-F motherboard. I recently got a new video board for it, and I was thinking while I'm upgrading that, I might as well put in another M2 SSD stick, because right now I'm running 250Gb in one M2 slot, and I have a spare M2 slot. Then I thought, hey, I wonder if my motherboard can handle setting up two M2 SSDs in a RAID0, and get a big performance boost. So I do a little research, and it turns out, the second M2 slot takes it's bandwidth from my video board slot. Of course, I have been running my SSD in the second slot this entire time, since I didn't realize this would happen and just picked which slot I wanted it in at random. So I've had my video board at x8 instead of x16 this entire time and didn't notice, probably because my old computer was so old anything feels like an upgrade from that.
So I think I'll avoid using the second M2 slot and just get a bigger SSD instead of using both slots and giving up half my video card bus.
I should have read the manuals a lot more carefully when I built this thing.