please help!! Windows PC problem

hello, I’m looking for help with my computer. Recently, I just moved across the country and I had to ship my computer. as soon as I booted it up after getting it there were green artifacts across my screen. My computer worked fine and i was able to play games despite that. Then my pc shut down i got the green artifacts once again but this time windows disabled my graphics card and i got error 43. there don’t seem to be any visible issues to the eye but perhaps internal. I did basically everything as far as my skill goes. For example, I tried to reinstall the drivers. I tried reseating the GPU. I checked the wiring. And I tried anything possible that I know of. I ended up trying to get help from my stepdad and after putting the computer on its side, it worked. But it stopped working again. I cannot tell if laying it down helped it at that moment or it was pure luck, but either way it stopped working once again. i’m a full time college student and i do my homework and gaming on that so i really need help. I was thinking that it was because of sagging in the GPU, but if that was the case, I feel as though my computer would be working while on its side as it was at first. So it seems there may be an issue i cannot pin point myself. I’m not very knowledgeable in this area. i have had this pc for 5 years and perfect condition until shipping. but it did work for days after getting it from shipping.

my specs
gpu : nvidia getorce rtx 3070

motherboard : b450 aorus pro wifi

cpu : amd ryzen 5 5600 x 6-core processor