I'm looking to upgrade the fan in my device from a 2-pin model to a 4-pin PWM fan to enhance cooling performance. The current setup uses a 2-pin fan where the speed is controlled by varying the voltage on the 12V line. I want to know if I connect a 4-pin PWM fan to this 2-pin header (using just the 12V and Ground wires), will it still work and adjust the speed based on the voltage variation?
2 Answers
So, just to clarify the pinouts: you've got GND, +12V, TACH, and PWM. Without connecting the PWM signal, your fan will likely run at 100% speed constantly.
You might run into some issues with starting voltage. PWM fans often require a higher starting voltage compared to standard fans, which isn't always mentioned in the specifications. Your current fan probably works within a range of 3-12V, but the PWM fan might not even start until around 7V, meaning you could lose cooling at lower speeds.
Thanks for the insight! I looked up my current fan and found it runs between 6-12V. The PWM fan I'm considering starts at 3.3-12V, so I hope it will work fine.
But if the device adjusts the voltage to control the speed, won't the PWM fan vary its speed based on that voltage? If it's fed 10V, will it still not slow down?