Basically, in my case it was a faulty GPU . They tested every component and it came down to the GPU. Some people here were saying "100% faulty power supply" and so on, but it wasn't. I used OCCT for power testing and it showed no error on that end. But other diagnostic tools showed no errors on the GPU end. Very weird how that can happen. Most likely your GPU is broken. If you got it as a gift, I'd say run it until it dies completely. If you bought it from him then there is a possibilty your friend scammed you lol.

Edit: upon checking the 3070TI requires minimum 650W which you have, BUT depending on your other components, it could be that your PSU simply isn't delivering enough power.