I've been thinking about getting new fans for my case but I don't know the difference between a 3 pin fan and 4 pin.
A four pin fan can be controlled in Bios thru your Fan curve controller whereas a 3pin fan requires a hub to control the voltage DC. You can plug a 3pin fan into a four pin header however no control in Bios. Some Motherboards now do have DC control in Bios or thru the case power switch.
The
three wire connectors are for small chassis
fans with lower power consumption. The four
wire connectors are for processor
fans with higher power consumption. ... Note: When connecting
a three wire fan to a four
pin fan header, the
fan is always on; there is no
fan...