sorry for late response, I have marked the solution but will summarise it in 1 sentence, reinstall windows.
I think its a virus that came with a program that you've downloaded.
From what I can understand, the virus 'latches' onto a vital part windows 10 (in this case, "system"), so that it can hide with system processes, and when an application is loaded (I have no idea why its specifically Minecraft) the virus 'activates' and starts using the graphics card to start mining for digital currency or something of the sort.
Inform me if my explanation is wrong because this is all inference.