Originally Posted by Kylecondo
I bought an assortment of 48v 120mm fans. I plan to power them via a wall-wart transformer but I would like the computer to be able to adjust power flow to them so that they are not running at 48v all the time (extremely loud).
for the record these fans are mounted to an external radiator to cool my mineral immersed computer
Unless they are PWM fans you will not be able to control them well from a motherboard.
Only Gigabyte boards have Voltage control of fans (they also have PWM control). They max out at a nominal 12v - one fourth of the expected Voltage of your fans. All other mb's have PWM only. If your fans were PWM fans they could get their 48v somewhere and get their pwm signal from the mb.
But don't try to power these from your mb. Max allowed Amperage is somewhere from 1 Amp (Gigabyte) to 2 Amps (As.s). Your fans probably each draw more than 1A, and possibly more than 2A.
You might be able to hook up a rheostat between your 48v source and your fans.
ONe last thing: I had some 24v San Ace fans. They clicked loudly at 14v. Unsuitable for computer use. Yours may do the same.
BTW - what are the model numbers of your fans?