I have a Core2 Quad 2.4GHz that I use as a small-ish home server. About half a year ago, the power supply died, and when I replaced it, I left the chassis open

I have a Core2 Quad 2.4GHz that I use as a small-ish home server. About half a year ago, the power supply died, and when I replaced it, I left the chassis open and noticed the CPU fan was no longer rotating. At first, I was really scared, but the machine is running well to this day. On a hot day, the system log will show many messages about the CPU reducing its clock speed to prevent overheating, but that seems to work well enough. (The system, to be fair, mainly runs as a file and DNS server, so it is not exactly super-busy, but still. It might also help that the fan sits on top of a huge heatsink.)