Hello bro I will give you a few more ways that you can try to fix this issue.
1. Try downloading older drivers. The newest AMD drivers sometimes bug a lot so it might be a good idea to install older drivers which are more stable.
2. Maybe your RAM is the problem. Sometimes new built PCs have their RAM setup on the wrong frequency. For example, my RAM is 3200 MHz but the speed at which it was running was 2666 MHz. To fix this you should set the RAM speed to speed on which it is supposed to be. You can check that by looking on the RAM sticks themselves or by using programs that can help you with that. You should also enable XMP/DOCP which will help you with RAM speed management. Tutorial on how to do that is here: How to enable XMP/DOCP
3. Your GPU is maybe overclocked. Go to Adrenalin Software then go to Performance tab and then click on Tuning. Then select Custom tuning option. Scroll down and enable GPU tuning and then set your max frequency to -10%. Then go to VRAM tuning and enable it as well and lower your max frequency a bit. Mine was on 1750 MHz so I lowered it to 1600 MHz. Then save the changes.
4. Monitor can be a problem as well. This is the one thing that actually solved my issue with this. I used an old monitor that didn't even have an HDMI port, so I had to use an adapter. This probably could not work with my new RX 580 GPU, so it kept shutting off and uninstalling my drivers as well as resetting my custom tuning setting to default every time. So I got a monitor that has an HDMI port and so far, the problem seems to be solved.
I hope one of these solutions will help you. I know your feeling of having an expensive PC that can't run a single game as it is intended. If none of these solutions work, you should probably seek professional help from a person that understands software more than your average forum guy. God bless!