In the middle of 2018 I bought myself a desktop computer, the first one I had since years. However I have had constant trouble since. Already after a few months, the machine slows down tremendously, and it seems like formatting is the only way to fix it. I have used diagnostics tools and it seems like its impossible for any hardware to be at fault. It seems to be software related, but I don't do anything different than I did on any laptop throughout the years, and those never had any issues.

Does anyone have any guess as to what could be causing this?