Not even tech store knows whats wrong.

PC crashes when running any GPU intensive application. Running 3DMark CPU test runs fine but when I run one that tests GPU as well, it will crash. The crash is just a black screen, everything else still has power.
Took GPU separately to tech store first, and they said its fine.
Took whole PC in, and they were able to replicate the crash. They returned it "fixed" but their method was removing and plugging back in the GPU, and told me they dont know why it was crashing.
1 month later now im getting same black screen, and feels like more often.

3070 with a 5600x