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Topic Title: Is It Possible to Control My CPU Fan Speed?
Topic Summary: 3-pin stock fan only runs between 3,245 and 3,375 RPM
Created On: 09/19/2007 10:12 PM
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 09/19/2007 10:12 PM
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senecalakemonster
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I recently posted a topic thinking that AMD Cool n' Quiet was not working with my new motherboard (click here to see topic). I've determined that it is working, but I can't determine is why the CPU fan runs at an almost constant speed between 3,245 and 3,375 RPM. My main complaint is that it is quite loud. I don't really have a problem with a fan that "over" cools the CPU.

My motherboard is an ASUS A8V-XE and does not appear to support the QFan CPU fan control. As mentioned in the other topic there is no QFan option in the BIOS, and "Enable QFan" is not selectable on the PC Probe II GUI. Does anyone have a suggestion as to how I can control the fan speed? The fan is the stock CPU cooling fan that came with my AMD Athlon X2 4200+ (Manchester). I have seen an application called SpeedFan, but I don't think it works correctly with my motherboard. It was reporting CPU fan speeds around 26000 RPM. It's a three-pin fan and not one of the four-pin fans about which I have read. Also, the motherboard does not have a 4-pin fan connector.

Maybe I'm just complaining too much about the fan noise and should be glad that I don't have the opposite problem and an overheating CPU. Nevertheless, these speeds do not seem reasonable for a CPU that idles between 34 and 36 degrees Celsius. Note that the CPU fan speed does not increase at all when the CPU is under load (around 49 degrees Celsius). I know this might be more of a question for ASUS, but I'm quite certain I'll get responses of higher quality sooner on the AMD forums.

Thanks!
 09/20/2007 12:53 PM
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kazgirl
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Hi there,

My understanidng is that normally the fan speed is adjusted via a voltage regulator on the mobo which responds to the temperature via a temp sensor, increasing or reducing the voltage to the fan to increase/decrease the fan speed as needed.

If your mobo isn't doing this I would think that there is a fault with the mobo....and that an RMA is needed.

Cool 'n' Quiet is more to do with CPU voltage and speed, and is mainly a Power management utility, for achieving power savings....with the reduction in power being used also comes a reduction in the heat generated, hence the 'Cool' and with the cooler temp meaning slower fan speed hence the 'Quiet'....

As far as I'm aware all Q-fan does is to allow the user to set the maximum fan speed at a range of settings lower than the default fan max speed, i.e a fan with a max speed of 3000rpm would be 16/16, the settings for cpu fan in Q-fan are 15/16, 14/16, 13/16....down to 11/16, with each reducing the max speed of the fan acocdingly....down to a max reduction of about 31%, so a 3000RPM fan would be slowed to 2100RPM at the lowest 11/16 setting in Q-fan...but this wouldn't affect the fans operation which would still be regulated by the mobo voltage regulator and temp sensor in combination, but the temps would be a bit higher now due to the slower fan speed, so the fan would be more likely to run at max speed at more frequent intervals....

It could be that you just have a noisy fan, or that your HSF is not mounted correctly causing a higher than normal CPU temp which the fan is having to run continuously at the max speed to maintain a safe temp, this is the most likely explanation.

Try reseating the HSF to see if it helps, if not then I think an RMA is called for.

Hope this helps.

Kaz
-x-

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3DMark06 = 20717 / 3DMark Vantage = P13618 / My Overclock Guide / My Troubleshooting Guide
 09/20/2007 04:59 PM
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Stern63
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Kazgirl, you cover pretty much all of the basics and this is good.

I must say I still have problems with such basic system functions though.

Most motherboards today seem to have "intelligent fan speed control". Question is how to utilize it.

First instance I encountered was with Asus a8n-sli dlx, the bios utility called QFan. I found this quite ok at controlling fan speed for cpu in particular. A premium MB at the time. I have great use of it still now that I upgraded to Opteron 185 on that board, I just had to use a normal mid-speed fan instead of the supplied temp-controlled fan to make the fan contol work.

Second instance was on a build based on an Abit s754 board, mATX. Pretty much budget but featured a fan utility that was actually much more advanced, much more options than this previous Asus A8n dlx board and the QFan utility. Excellent fan control.

Third instance, a biostar MM, 6100 M9. Socket 939 but surprisingly no intelligent fan speed utilities supplied although it is the latest design of them all. I still have some hopes to use speedfan or similar utilities to get the intelligent fan speed control that I need. The alternative in this case is to get a cpu cooler that has great over-capacity to enable a constant low-speed large fan to cool it regardless of actual cooling requirements. I really hate this unintelligent cooling alternative.
 09/20/2007 05:33 PM
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kazgirl
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Hi Stern thanks,

Yes...I think I know what you mean....

I'm just wondering whether or not adding a resistor in-line between the mobo fan header and the fan would have the effect your after....

Thinking about it I'm not sure it would as the voltage regulator would still be controlling the voltage supplied to the fan header, and so even though the resistor would then drop the voltage being supplied to the fan would this slow the fan too much...

I think the only way to do it where there was no BIOS support to enable/disable this aspect of the fan control, would be to do a mod to the mobo itself by bypassing the particular voltage regulator cicruitry responsible....something which is way beyond me I'm afraid...

I think it could be done by someone suitably qualified and with the proper PCB schematics to identify the various connectors....but its way out of my league...lol.

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3DMark06 = 20717 / 3DMark Vantage = P13618 / My Overclock Guide / My Troubleshooting Guide
 09/20/2007 07:47 PM
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Stern63
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Yes Kazgirl, this is not easy. Then again, how hard is it really.

The majority of reasonably modern MB:s out there have supporting circuitry to regulate cpu fan speed. Utilities like fanspeed can be used to utilize the opportunities.

If the stock coolers were able to just do what they are told to do, there would be no problems at all. But no, they decided that it would be a great idea to include a temp sensor-controlled fan, in which the actual fan speeed is regulated by - the temperature of the air that is sucked into the cooler!

If anyone asked me, I'd say this is insanely stupid since it has almost no connection to the object of control here, core temperature. It simply cannot work. And it doesn't in fact work, at least not to my limited experience.

To be able to use those stock cooling solutions it is necessary to find ways to circumvent the temp sensor fan. Like scrapping it and replacing with a normal fan, not temp-sensor controlled. The other alternative is to get a third-market cooling solution that don't use those crude and ineffective control schemes.

Damned. If AMD only supplied a normal fan with the stock coolers there would be no problems at all. No temp-sensor fans, this is just so extremely uninformed given the ways we use to control fan speeds today. We need intelligent fan control, with the objective of keeping *core temperature* below a certain limit.

How hard is it to provide stock cooling solutions that plug right into these pre-existing and perfectly functional systems?

PS. That's a really impressive rig you got there, Kazgirl! 3.45 Ghz. Damned good indeed.

Edited: 09/20/2007 at 08:07 PM by Stern63
 09/20/2007 08:32 PM
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Camthrax
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if you'r really wanting to get serious about this fan controll thing, then plug the fan in to a fan controller instead. get a new fan for it, if you have to. then, either use monitoring software, or a thermal sensormagigy, and turn the fan up or down as neccesary.

or get liquid cooling without a fan. *flees*

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 09/21/2007 01:46 PM
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Stern63
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Camthrax, what we want is simply to have intelligent fan control which means that fan speed is regulated automatically to keep the *core temperature* below a certain limit.

At idle, the fan spins very slowly. Even slower if Cool&Quiet or PowerNow is activated. At full load the fan spins fast enough to prevent the cpu from exceeding the set target temperature, 57C for instance.

This is what you get with Asus QFan, Abit's counterpart, Speedfan and other utilities that are compatible with your MB's sensing & fan control chips. Some utilities also allow the user to set minimum fan speed, and to fine-tune the response curve fan speed vs temp, but even the basic QFan as implemented on asus A8N for instance is good enough for most purposes.

These are excellent and very well-functioning control systems. Naturally they can only work as intended if the fan responds with higher rpm when the controller asks it to spin up, and vice versa. If you have a fan with a temp sensor like on many AMD stock coolers, this intelligent fan control is not possible anymore and you get unpredictable fan behavior that can lead to both unnecessary noise and cpu overheating.

Back to the question of this thread: you need to do two things to get this intelligent fan control to work IMO (assuming you have a mainboard with fan speed control hardware built-in but no bios options such as asus QFan available, or manufacturer-provided utilities for fan control):
1. Make sure there are no temp-sensor fan on your cpu cooler. If you need to replace the fan, make sure it is sufficiently powerful at full speed to cool the cpu under all possible circumstances. Alternatively, buy a good third-party cpu cooler that has a "normal" fan (without temp sensor).

2. Install and configure a compatible fan control utility. My personal favourite is Speedfan. You have to google for information of how to set it up correctly for your chipset and fan configuration. It doesn't support all fan control/sensor chips out there but quite a few.

Good luck!

PS. What you say about reported fan speeds by Speedfan is nothing to worry about. You have to go into the "advanced" tab, selecting your fan control chip and configure dividers for the sensed rpm signals. While you are there, you also need to configure control method "Software" for the cpu fan and the possibly other fans that you are interested in controlling with this program.

Edited: 09/21/2007 at 01:58 PM by Stern63
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