Why can the 3090 video card not work correctly?

Question

Video cards

Good afternoon. A friend took the 3090 and put the mother and i7-9700k into the z390 computer. Before that it was 2080. The indicators have dropped decently, what could be the reason for this?

Answer 1

Perhaps the mother and the video card could not agree on the speed of the pci-e bus and chipped in 1.0, look through gpu-z
in this place it should be pci-e 3.0 x16 or x8

Answer 2

PSU is not enough for the first 650W for the second 850W.