What causes graphics cards to not work in a PCI-E x16 slot?

Question

Video cards

I bought a new gigabyte B450M DS3H V2 motherboard and video cards do not start on it (there are two plugs gt210 silent and radeon 4850 x2 mobility).
Initially I thought it was a bios problem, but after the update the problem did not disappear.
Then I found out that this problem could have arisen due to bent processor legs
(in my case, ryzen 3 1200), but this version also disappeared after checking the stone.
The slot itself is working (I inserted a wi-fi adapter into it (pci e x1 device)).
Please suggest how it is possible to solve this problem, or at least point out the reasons for its
occurrence (MB some tracks on the slot are beaten? Then how to detect it?).

Answer 1

1. Is the card visible in the operating system?
2. In the BIOS, in the "Peripherals" tab -> " Initial Display Output" item : what is indicated?