Corsair H60 + Sp120 Performance Fan Question

Here's what you misunderstand. BOTH 3-pin and 4-pin (PWM) fans CAN have their speed controlled by a mobo header. The important factor is the the METHOD of control is different for those two fan types. A 3-pin fan's speed can ONLY be controlled by changing the voltage supplied to the fan on its Pin #2 - this is called Voltage Control Mode, or sometimes DC Mode. A 4-pin fan ideally should be controlled by PWM Mode instead. In this newer system, the fan always receives a full 12 VDC supply on its Pin #2, but it also receives the PWM signal on the added Pin #4. Inside the fan motor is a small circuit board including a chip that modifies the supplied power using the PWM signal to reduce the fan speed as directed. (As a side item, a 4-pin fan's speed CAN be controlled using Voltage Control Mode, although it's not quite as effective as using PWM Mode.)

Now, you have 3-pin SP120 fans, so they must be controlled using DC Mode. Virtually ALL current mobos offer an option on the CPU_FAN mobo header to use either PWM Mode or DC Mode, and you can specify which in BIOS Setup. Some even claim to detect automatically which fan type is plugged in, and set themselves. So here's how I suggest you set your CPU cooling system.

1. Connect the Pump unit of your H60 system to a mobo CHA_FAN header. In Bios Setup, set this one header to Full Speed (not "Standard" or "Automatic") so it will always send the full 12 VDC to your pump - that's what it requires.
2. Connect your SP120 3-pin fans (on the radiator) to the CPU_FAN and CPU_OPT headers. In BIOS Setup, set both of these headers to DC Mode and to use the "Standard" profile so the mobo will automatically adjust the speed of both fans according to the temperature measured inside the CPU chip.
3. Any other case ventilation fans should be connected to a different CHA_FAN header. Set this header to DC mode if they are 3-pin fans, or to PWM Mode if they are 4-pin fans. Set to "Standard" profile so they can be automatically controlled according to a different temperature sensor built into the mobo.

If you need further info, post back here exactly what mobo (maker and model no.) you have so we can look up its manual for details. Also post what fans you are using for case ventilation.