I have an Asrock K8NF6G-VSTA running XP. It has a 4-pin PWM fan header for the CPU. I'm running the heatsink passively, so this fan socket is empty.
I have some PWM fans arriving tomorrow afternoon, and I want to use that mobo socket to test them. The fans have a 400mm lead length, 15-16 inches, so I can plug them in thru the dremeled exhaust port and set the fan on top of the case.
The problem is, how to control the PWM signal for test purposes. Not even the bios allows that to be directly controlled. I'm hoping there's a utility that will allow me to set whatever PWM ratio I want, at least in the 30% - 100% range.
What I want is a utility package that ideally would control only the PWM speed, width, signal (whatever you want to call it) without any other side effects. I have SpeedFan 4.32 and RMClock but am not familiar with any PWM fan control capability they might have.
Can anybody point me in the right direction?
Mobo PWM fan header - how to control?
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Felger Carbon
- Posts: 2049
- Joined: Thu Dec 15, 2005 11:06 am
- Location: Klamath Falls, OR
SpeedFan will do it without you even needing to set anything up: When you first start the program, there will be a bunch of spinners just above the voltage displays at the bottom. They control the PWM duty cycles that are available on your motherboard. Some of them may not be connected to a fan header and thus do nothing, but if the motherboard is capable of controlling CPU fan speed then one of them will do that.
It will allow control from 0-100%, but note that 0% duty cycle may not result in zero fan speed (it's up to the fan manufacturer how it wants to handle duty cycles that would put the fan below its minimum speed).
Alternatively you could build a PWM generator, like the one on cpemma's site (which would need to be adjusted slightly for the ~25kHz frequency that PWM fans expect, and obviously sending the output to the fan's PWM input instead of directly to the motor). That would be more flexible, allowing you to test how the fan reacts to both different pulse widths and frequencies without needing a PC.
It will allow control from 0-100%, but note that 0% duty cycle may not result in zero fan speed (it's up to the fan manufacturer how it wants to handle duty cycles that would put the fan below its minimum speed).
Alternatively you could build a PWM generator, like the one on cpemma's site (which would need to be adjusted slightly for the ~25kHz frequency that PWM fans expect, and obviously sending the output to the fan's PWM input instead of directly to the motor). That would be more flexible, allowing you to test how the fan reacts to both different pulse widths and frequencies without needing a PC.
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Felger Carbon
- Posts: 2049
- Joined: Thu Dec 15, 2005 11:06 am
- Location: Klamath Falls, OR
Thanks. With Quiet Fan running, "Speed 02" is 90% with Fast set in bios, 80% Medium, and 70% Slow. So at least Speed 02 seems to be reporting something CPU-fan related. I can't see if I can change an actual fan speed until I get the PWM fans, but until then I'm all set.
BTW, Asrock provides no documentation at all on Quiet Fan. Evidently the fan speed is controlled on one side or another of a CPU temperature trip point. I googled and found two reviews of Asrock mobos that explained which side the variable speed applied (above trip or below) and I discovered the two experts disagreed on that point! Heck, I mever nake misteaks!
BTW, Asrock provides no documentation at all on Quiet Fan. Evidently the fan speed is controlled on one side or another of a CPU temperature trip point. I googled and found two reviews of Asrock mobos that explained which side the variable speed applied (above trip or below) and I discovered the two experts disagreed on that point! Heck, I mever nake misteaks!