hegde_atri

Try the Linux thing first to eliminate windows

Then if it works fine try reinstalling windows.

It may also be that power supply, won't know for sure without swapping it if you have a friend with one, or a local PC shop can just loan you one.

Probably a windows bug as I said above

You can see what happens under Linux by making an Ubuntu USB, if there's no problems there blame windows. It's easy enough to install steam and do some stress testing or just leave it running for a while.
 
Could also check your windows event log
 

You should have just gotten an R5 2600 and used the stock CPU cooler, that'd be like a $200-300 GPU right there...and that power supply is of questionable quality, but it's probably fine up to 400W at least.

For the GPU just find a used RX 470/480/570/580 on ebay or something, it'll be pretty cheap and still fine for 1080p gaming.

Just avoid the MSI armor unless it's cheap and 8GB as it's cooler is tiny.

There is nothing out of ordinary about what you described. Physics yo.

Thanks a lott mann. Truly appreciated