Basically just the CPU fan, case, and PSU (if you're lucky). If someone can figure out how to get Doom running on just those 3 things, young people will be able to ascend.
I also use Arctic fans, and they're by far the quietest, best-performing fans I've ever used. Equivalent Noctua fans are like 4-8 times more expensive, so unless they can also give handies or something, I can't imagine them actually being worth the price.