pcie slot not working

Hi there, I have been having issues with my PC randomly restarting (no bluescreen, just black and instant restart) for some while now. It occurs randomly in idle, light use or gaming and realiably in Stresstests (Furmark2 + CinebenchR23 all core). System: AMD Ryzen 7 5800x3D XFX Speedster MERC...

<SOLVED> I've had a motherboard for a while that has had a problem... The top PCIE x16 slot works with an old GT 710 (pcie 2.0x8 runs @x8) but not a gtx 1650 (pcie3.0x16). Both gpus work Chipset x16@x4 slot works with both GTX 1650 does not have power connectors I doubt it is a psu issue BIOS...

For some reason on my new computer, the GPU will not work on the top PCIE slot. I have literally replaced/returned every single bit of hardware except for my SSD and I have no idea what the issue is. I have reinstalled windows multiple times and have ensured all my hardware works by testing it...