Extended rpm range with PWM+Variable voltage

Control: management of fans, temp/rpm monitoring via soft/hardware

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nonhinged
Posts: 6
Joined: Sat Nov 10, 2018 10:58 am

Extended rpm range with PWM+Variable voltage

Post by nonhinged » Sat Nov 10, 2018 11:12 am

A while ago I made an adapter cable where the tacho and PWM leads connects to the Cpu Fan header and the power leads("+"/"0v") connects to a normal case fan header. The Cpu header outputs a PWM signal, and the case fan header outputs a variable voltage, this controls the speed of the radiator fans(water cooled system).

Tinkered a bit with the fan curves in bios and ended up doing a graph. With only PWM I can get the speed down to ~745rpm and with only variable voltage I can get the speed down to ~315rpm(reasonable reliable), with both the speed gets down to 235rpm.
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CA_Steve
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Re: Extended rpm range with PWM+Variable voltage

Post by CA_Steve » Sat Nov 10, 2018 11:34 am

Welcome to SPCR.

Fun tinkering. What's the fan make/model?

Does the fan reliably start up at the 235rpm point or do you have to start it at a higher point and then slow it down?
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nonhinged
Posts: 6
Joined: Sat Nov 10, 2018 10:58 am

Re: Extended rpm range with PWM+Variable voltage

Post by nonhinged » Sat Nov 10, 2018 11:57 am

It's EK-Vardar F3-120 fans.

The motherboard runs all fans at full speed for about a second during boot before they slow down. If I manually stop a fan after boot it won't start again at that low setting.

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