Stop PWM noise with speedfan

Just an ordinary rabbit · Post by **Just an ordinary rabbit** » Fri Jun 25, 2010 8:25 am

I recently discovered that Speedfan can be used to stop PWM fans from making a high pitched noise, and thought I'd share it.
This will only help with noises caused by the Pulse Width Modulation system, so will not help fan bearing noise or DC powered fans.

Disclaimer: Please try not to break your computer. If you do I take no responsibility because it's your fault and I've already broken enough stuff

. When I tried this on my system I didn't notice any changes in fan speed or anything else, so it appears to be fairly safe. If for some reason doing this causes damage to your computer I take no responsibility. I am now immune to being sued, yes?

In Speedfan, click "Configure" and then open the "Advanced" tab. Select the appropriate chip and you should be presented with some PWM control options. Look for "(Fan) PWM Base Freq."
By default, the base frequency for the PWM fans in my system is 23.4KHz.
20KHz is supposed to be the highest frequency humans can hear, but at 23.4KHz I can still hear the noise. Adjusting the frequency will change the tone of the noise, so adjust this setting until your fan ceases to squeal at you.

For those who have yet to be enlightened, Pulse Width Modulation is a system which controls fan speeds by turning them on and off again at a high frequency. Some fans produce a tone at certain PWM frequencies, which is very annoying when you have been burdened with unusually good hearing. (I can also hear high pitched noises from ultrasonic cat repellers and CRT TVs which everyone else seems to be immune to

)

Hopefully this info might be useful to someone

themaster1 · Post by **themaster1** » Fri Jun 25, 2010 12:40 pm

I can't find the option: (Fan) PWM Base Freq.
I use the version 4.40

I have several options: PWM 1 mode, etc, PWMOUT clock, Reverse PWM logic stuff like that..

Just an ordinary rabbit · Post by **Just an ordinary rabbit** » Fri Jun 25, 2010 1:45 pm

@themaster1
Sorry I forgot to mention that this might not be supported on all motherboards.
Version 4.40 is the current version so that shouldn't be a problem.

Just to clarify, the exact text for the CPU fan is "CPU0 Fan PWM Base Freq.", there will probably be "Sys Fan" or "Aux0 Fan" values too.

EDIT:
Screenshot:)

themaster1 · Post by **themaster1** » Fri Jun 25, 2010 2:03 pm

Nope i can't find that, i'll stick to my fan controller

Dxun · Post by **Dxun** » Sun Jun 27, 2010 12:20 am

Indeed, I can't find that one either, but is there any other way to control speed of a PWM fan at all?

My chip (IT8718F) supports only three PWM modes (Software Controlled, SmartGuardian and ON/OFF). Neither of these modes results in any responsiveness from Speed0x controls at "Readings" tab of SpeedFan.

Any suggestions or help?

Thank you

lodestar · Post by **lodestar** » Sun Jun 27, 2010 10:18 am

I think the developer of Speedfan has done a great job, bearing in mind that different sensor chips have/don't have particular functions, and also that the way that sensor chips are wired to the motherboard fan headers varies from manufacturer to manufacturer. So it's not really Speedfan as such, it's the Winbond W83627EHF v ITE IT8718F, etc, etc.

In terms of alternative ways of controlling PWM fan speed there is CPUID HWMonitor Pro from http://www.cpuid.com/softwares/hwmonitor-pro.html which costs, but you can try free for 30 days. Note this is just a straightforward manual control over PWM duty cycle % in 5% increments, 0 to 100.

A hardware solution is the Scythe 120mm SlipStream variable PWM fan, see http://www.scythe-usa.com/product/acc/0 ... etail.html where you set the PWM fan band with a rotary PCI slot control. It means buying a replacement fan of course. In use you can just dial in the idle speed you want down to around 500 rpm. At this speed it is effectively silent. If the CPU gets hotter then fan speed as normal will increase automatically, so you can have both a motherboard controlled PWM fan and some manual control over what speed the fan runs at.

This fan is also supplied by Scythe with their Yasya CPU cooler, and will be fitted to the upcoming Ninja 3.

singingbush86 · Post by **singingbush86** » Wed Jun 30, 2010 9:09 pm

Very helpful. Thank you!

themaster1 · Post by **themaster1** » Thu Jul 01, 2010 5:31 am

Dxun wrote:My chip (IT8718F) supports only three PWM modes

CPUID HWMonitor works with this chip, i have the same or close (ITE IT87)