So I'm building a new PC for the 3070, but am using my old Fractal Design Arc case to save money (not to mention I love it). It's 5 years old, but the four 140 fans mounted within are running fine. My question is: Should I just replace all fans, or just maybe buy an extra and deal with fan failures as they come? Is there a rule of thumb here, or am I over-thinking it? Thanks!