So the computer gave me another "fan not detected" warning. I pressed F1 to start. It's not really loud or anything. The only thing that was odd about it is that the computer froze right in the middle of what I was doing.
Is it a desktop/tower or a laptop? Also is it a chassis fan, a CPU/GPU fan, a motherboard fan, a power supply fan? Most fans should be easy enough to replace if you can locate which one, its size and specs.