you can plug any fan in there and it will work. They are labeled because when you go into the BIOS, you will see fan monitors labeled CPU_FAN, SYS_FAN, PWR_FAN, etc.. and it corresponds to the fan connected to those fan headers. Most of them don't matter but some motherboards will give you a warning if it doesn't detect a cpu fan so it is best to make sure the cpu fan is actually in the CPU_FAN header but the other headers are fine for whatever you want.