

Sincerely sounds like your cpu fan doesn’t have a good connection with the cpu.
Shut it down, unplug, remove the heatsink fan (hsf), clean top of cpu and bottom of hsf and apply new thermal compound as 5 dots (center and edges) to the cpu.
Then remount the hsf and let sit for 15 minutes before powering on again and monitor temps.
Better would have been:
Handful of users complain about 3rd Party Cables Melting Their 5090FE.