Is my gpu defective?

I have had the problem with fortnite that when starting a lap sometimes the FPS number was very inconsistent and quite low although I used ne rtx2080ti. If you restart the game then everything works fine. However, the problem also happened with my old PC, so I'm wondering.

This happens to me a few times it happens that the monitor goes out again and then I have only 60 FPS battlefield. But also had the assumption that it could be because my TV was also connected and Battlefield adjusts the FPS number on the screen.

So worried I got when already 2 times when the pc's screen turned on no signal

Update graphics drivers and put them on DirectX 11 because 12 is buggy

Did you update your drivers?