Case fans - DC or PWM?

[dgmulf]

My motherboard BIOS has an option to choose whether my fans are controlled via DC or PWM, and I cannot find any information in my case manual that specifies how the fans should be run.

I have a Phanteks Enthoo Pro, which comes with a front intake and rear exhaust.

(And I'm assuming my Swiftech H240-X AIO water cooler gets PWM from the CPU fan header?)

 

[OlyAR15]

All the pwm fans that I've seen have a 4 pin connector. The case fans of the Enthoo Pro are not PWM controlled.

 

[BonzaiDuck]

My motherboard BIOS has an option to choose whether my fans are controlled via DC or PWM, and I cannot find any information in my case manual that specifies how the fans should be run.

I have a Phanteks Enthoo Pro, which comes with a front intake and rear exhaust.

(And I'm assuming my Swiftech H240-X AIO water cooler gets PWM from the CPU fan header?)

Yes, to the last question, but I have a suggestion just for that.

This is my personal opinion. We'd like to avoid using third-party fan controllers -- some communicating with the board and processor -- many more which don't. The latter require cluttering your case and parts with thermal sensors, and it is even a greater pain to install them in places where they record the temperatures needed to make the fans respond robustly.

It's just extra complexity.

So -- my personal opinion. You are best to define a case airflow strategy that uses mostly PWM fans. Even so, some boards, like my ASUS, allow either DC (voltage) control of 3-pin fans, or PWM control of PWM fans. there are often additional fan-ports exclusively for the 3-pin variety.

If you incline toward narrowing your fan search to PWM as first priority, and then choosing some 3-pin-voltage-controlled fans for remaining intake fans, then look at the $10 Swiftech 8W-PWM-SPL-ST splitter device. You can power the fans or pumps directly from the PSU, but CONTROL them off the single CPU_FAN port (PWM, of course). The splitter will not work with 3-pin fans and will only run them at full bore. But you can add up to eight PWM devices -- of VARIOUS 12V amperage -- and control all of the devices as % Duty Cycle. This includes both PUMPS and fans of the PWM variety.

Only the device plugged into the first "red" port on the Swiftech can be monitored. But you could run the yellow tach-wire of any of those fans to a vacant motherboard fan port. The board should monitor those fans, but there would be no voltage draw from the board. Nor would there be any voltage draw for the Swiftech device from the motherboard.

Nifty little item . . . . I just happen to think . . .

 

[dgmulf]

Thanks for the info. Bonzai, that sounds a bit advanced for me right now, but I'll refer to your post if I want to upgrade my fan setup later.

 

[wgusler]

Swiftech 8W-PWM-SPL is for PWM fans only?

 

[BonzaiDuck]

Swiftech 8W-PWM-SPL is for PWM fans only?

Apparently. If you attach three-pin fans, they'll only ran full-bore from PSU power with no PWM wire and a useless tach-wire, since you would want to have monitoring and control both for a PWM fan or fans.

The good thing about it: you can control pumps and fans of varying sizes up to the capacity of 8 devices. You can only monitor one. So the Swiftech might seem more handy or elegant if you were controlling identical devices. But if they're all controlled by the same phenomenon -- say the CPU -- you only lose full monitoring. If the CPU temperature goes up, you'd have both a pump and a fan operating at the same duty-cycle assigned for that temperature range.