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PWM fans don't adjust automatically

Tags:
  • pwm
  • case fans
  • Speedfan
  • Components
  • open hardware monitor
Last response: in Components
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August 25, 2014 1:13:47 PM

I have two 120mm Arctic F12 PWM case fans installed on the side of my Silverstone GD05B on an Intel DH67GD motherboard. The fans are plugged into the front fan header on the motherboard. The fans used to work with PWM - they automatically adjust as workload demanded and temps changed - but now, since I reinstalled Windows 8.1 a few months ago, they don't change on their own. I can change them manually with Open Hardware Monitor but that's annoying and not a good solution for when my kids want to play games but don't know how, or don't remember, to bump up the fans to 100% before playing.

(I used to use Speedfan on the last Windows installation and even had temp thresholds successfully set up but, like PWM on the fans, Speedfan doesn't work either - it can read temps but can't control anything.)

I'm wondering what troubleshooting steps can I take before trying new fans? Could new fans even make a difference?

More about : pwm fans adjust automatically

August 25, 2014 1:28:37 PM

Check your bios and make sure the chassis fan header is enabled as pwm.
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August 25, 2014 1:29:58 PM

Don't buy new fans. The problem is with a configuration setting in the computer. At the time of the windows install, did you update or change the bios at all? There must be a application that was installed previously that interfaces with the motherboard controls.
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August 25, 2014 2:52:36 PM

markwp said:
Check your bios and make sure the chassis fan header is enabled as pwm.


dwatterworth said:
Don't buy new fans. The problem is with a configuration setting in the computer. At the time of the windows install, did you update or change the bios at all? There must be a application that was installed previously that interfaces with the motherboard controls.


I double checked BIOS and everything was set right there. All three fan groups - Intake, CPU, and Outlet - were set to Auto (the other choice being Manual). One other interesting issue is that the side fan on the left of the case, a Noctua NF-F12, is plugged into the Rear header but no matter what I set it to - Intake, Outlet, Chassis - it always runs at 100% and it's the only fan I can't control with Open Hardware Monitor. I've researched this quite a bit today and found my way to the Intel forums, where folks talked about having Intel Desktop Utilities installed, so I've installed that as well. We'll see if that makes any difference. I'll post my results shortly.
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August 25, 2014 3:01:43 PM

Try swapping the fan leads to determine if it is a fan issue or a header/bios issue. If you can control the front via pwm but when you swap to the other fan using the front header and it doesn't work, then you have a fan problem. If both fans exhibit the same problem (no control off rear header), the problem will be either the bios setting or a potential bad trace on the m/b.
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August 25, 2014 4:06:34 PM

markwp said:
Try swapping the fan leads to determine if it is a fan issue or a header/bios issue. If you can control the front via pwm but when you swap to the other fan using the front header and it doesn't work, then you have a fan problem. If both fans exhibit the same problem (no control off rear header), the problem will be either the bios setting or a potential bad trace on the m/b.


I switched the "front" (Arctic) fans to the Rear header and it did the same thing as the "rear" (Noctua) fan - ramped up to 100% and can't be controlled manually via software. The "rear" (Noctua) fan plugged in the Front header didn't exhibit this behavior, so it's not the fan. I also grabbed a 4-pin splitter so I have fans from both sides of the case connected to the Front header. While they're not ramped up to 100%, they aren't responding to PWM - they can be controlled manually, but PWM isn't doing it's job. I'm guessing it sounds like a motherboard issue at this point? Is there any chance that this could be fixed, or would a new mobo be the only option?

Also, I installed Intel Desktop Utilities but that didn't seem to do anything for me. I also installed the newest version of Speedfan and set it up. It seems to be able to monitor temps correctly, and the fan speed percentage changes, but the actual speed RPMs of the fans don't actually change.
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August 25, 2014 4:43:54 PM

The only sure fire way to check and see if it is a m/b problem is to check the header via oscilloscope. Even if you could pinpoint that the issue is m/b related, cost to repair would definately be prohibitive. You'd be much better off buying either a new m/b, or getting a third party pwm multi fan controller.

Mark
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August 25, 2014 8:53:28 PM

Thanks for the feedback. One more question. I'm pretty sure your answer will be, "No! Don't be an idiot," but I've seen this suggestion on other posts and since you know a thing or two, I'll ask: Since I know PWM works on the CPU, would it be feasible to have all of the fans connected through the CPU header? Would there be a significant risk of damaging the mobo?
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August 26, 2014 12:23:26 AM

Turns out, I didn't need to try plugging everything into the CPU header. After posting my last comment, and spending what has probably amounted to 3 full days (72 hours) worth of researching and tinkering, I finally figured out why Speedfan never worked - and it made me feel pretty darn dumb. I had to activate Manual controls in Speedfan > Configure > Advanced > select the chip with the fans > change "PWM 1 mode" to Manual. I found the key to the puzzle here in the third image: http://www.silentpcreview.com/article1275-page2.html After making that change, PWM is *finally* working.

What really makes me feel dumb is that as soon as I saw this solution, I remembered doing it before, years ago. I don't even know how many Google rabbit holes I went down to figure this out, but my last search was for "Smart Fan IV" which is the default BIOS configuration automatically selected in Speedfan. This was apparently preventing Speedfan from doing its job which, in turn, prevented the fans from doing theirs.

Unfortunately, this did not resolve my problem with the Rear header not working on anything besides 100% but, at this point, I can definitely deal with that.

Thank you Mark and dwatterworth for your expert advice!
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August 26, 2014 6:28:03 AM

Glad you solved it! That's the trouble with a reliable computer...you forget how to fix it!
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