Mysterious GPU behavior

[Tejdog]

Hi,

Sorry its long.

I have some problems with my GPU. I bought an Evga RTX 3070 ftw3 gaming and bought new RAM. I reinstalled windows straight away and everything seemed ok. Then I saw in device manager that Windows couldn't find any PCI drivers. So I downloaded the chipset from the manufacturer's website and the errors in device manager disappeared. I used the GPU normally for a few days and there was no problem. One day I played Cyberpunk for about 2 hours with no problem, then I turned it off normally and did some things in the browser. Out of nowhere the screen flashed and the PC restarted. After the restart, I had green artifacts on the screen and the GPU wouldn't load (it was visible in the device manager, but it reported error no. 43), I did a few restarts and suddenly it started working. The next day I turned on the PC and the same problem again, green artifacts, the GPU wouldn't load and the Nvidia control panel wouldn't load either. Now I turned on the PC again and the GPU wouldn't work, I restarted the PC and it worked again but the sound output changed from the sound card to the monitor (weird). I switched back to the sound card, the sound started to go crazy and the PC restarted and couldn't find the GPU again. Now it just sometimes loads and sometimes doesn't. When I put the old GPU (GTX 1070ti) back in, everything works normally. But somehow I don't think it's a faulty GPU, could it be the motherboard, or the power supply, or is the GPU dead?. Do you know what it could be?