More fan questions!

I've been wondering, when I removed my intel stock heatsink/fan, it had a 4-pin connector (not the same as connecting to the PSU). The CPU_FAN on my mobo has 4 pins also, but when I installed the BT which is 3-pin, it still fit because of the design. The manual lists the pins as: GND, CPU FAN PWR, CPU FAN IN, and for the 4th pin it says CPU FAN PWM. What is PWM? I'm just wondering all this because I haven't seen any fans available that have 4-pin connectors to the motherboard. I'm assuming the 4th pin allows speed adjustment because the stock fan could always go from 4800 RPM to 1800 RPM depending on temperature whereas the BT fan is always the same.

PWM stands for Pulse Width Modulation as far as i know

the way i think it works is this:
normal RPM changing lowers voltage, but fans cant run below a certain voltage
PWM always sends 12v, but uses intervals so the fan doesnt get 12v all the time.. (see it as the fan switching of for a really short time inbetween pulses)

again, not 100% sure about this ... hope to have helped

I've got the same thing on my intel mobo. You can use any fan that doesn't use to much power for the board. Jognt is right though. It's just a way to regulate fan speed but keep voltage at 12v.

Jognt said:

PWM stands for Pulse Width Modulation as far as i know

the way i think it works is this:
normal RPM changing lowers voltage, but fans cant run below a certain voltage
PWM always sends 12v, but uses intervals so the fan doesnt get 12v all the time.. (see it as the fan switching of for a really short time inbetween pulses)

again, not 100% sure about this ... hope to have helped

Click to expand...

very well explained

Oh I see... thanks for the info!