AB350 Gaming ITX CHA_FAN1 not working
Printed From: ASRock.com
Category: Technical Support
Forum Name: AMD Motherboards
Forum Description: Question about ASRock AMD motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=113500
Printed Date: 20 May 2026 at 3:23pm
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com
Topic: AB350 Gaming ITX CHA_FAN1 not working
Posted By: Granola6614
Subject: AB350 Gaming ITX CHA_FAN1 not working
Date Posted: 28 Apr 2026 at 4:13pm
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Hello, I have an ASRock AB350 Gaming ITX motherboard with a Ryzen 5 2600. It was running fine under UEFI version 6.20 but that was quite old and vulnerable to a number of attacks so I decided to update it. I first updated it to the bridge BIOS version 7.00, and then to the latest version 10.50 (dated April 8th 2026). The update went well but since then the CHA_FAN1 header on my motherboard stopped working. The fan connected to it works properly if I connect it to the two other fan headers of the motherboard. I really need all 3 fan headers on my motherboard to work because I want individual parameters for the CPU radiator fans, the water pump PWM and the rear exhaust case fan (connected to CHA_FAN1). My rear exhaust case fan is a BeQuiet Silent Wings 3 PWM 120mm. I made sure it responds well to PWM on the CPU_FAN header (accelerating, decelerating, steady speed etc). I have read some people experienced similar problems with other ASRock motherboards after BIOS updates and solved their issue by disabling USB Power On, but this did not solve the issue on my motherboard. I also tried loading system defaults --> no improvement I also tried clearing CMOS --> no improvement I then tried to roll back to BIOS version 10.43 Beta --> no improvement. I cannot roll back to version 6.20 since it is too old for a roll back (if I understand correctly). I also want to mention that this malfunction is independent of the OS. I see this behevior even before OS startup and when navigating the BIOS : the rear exhaust fan is stopped. I have taken a couple of screenshots in the BIOS. CHA_FAN1 speed is reported as "N/A". Could someone please help me solve this issue? Thank you in advance. |
Replies:
Posted By: Xaltar
Date Posted: 28 Apr 2026 at 4:48pm
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Have you checked in your UEFI under hardware monitor-> FanTuning and made sure "Chassis Fan 1 Control Mode" is set to PWM? If that fails then you can try https://forum.asrock.com/forum_posts.asp?TID=630&title=how-to-clear-cmos-via-battery-removal" rel="nofollow - this and see if that gets it working. Let me know how it goes. ------------- 
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Posted By: Granola6614
Date Posted: 28 Apr 2026 at 5:02pm
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Hello and thank you for your reply. I have tried to clear CMOS as you suggested but this did not change a thing : the CHA_FAN1 header is still unresponsive. |
Posted By: Granola6614
Date Posted: 28 Apr 2026 at 5:03pm
| Oh and as I mentioned in my OP, I have made sure to set the control mode for CHA_FAN1 to PWM. |
Posted By: Granola6614
Date Posted: 28 Apr 2026 at 5:21pm
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I have noticed that CHA_FAN1 is not even reported in HWInfo64, which makes me think this is a software/UEFI error. Here are the screenshots : When I was running v10.50 : https://imgur.com/v1YjNuO" rel="nofollow - https://imgur.com/v1YjNuO You can see "N/A" in front of CHA_FAN1 : https://imgur.com/5kHrue1" rel="nofollow - https://imgur.com/5kHrue1 And here is the screenshot of HWInfo64 with CHA_FAN1 missing : https://imgur.com/hh6iQtj" rel="nofollow - https://imgur.com/hh6iQtj (Sorry for the 3 replies in a row, this forum lacks the "edit message" function) |
Posted By: wino
Date Posted: 28 Apr 2026 at 6:18pm
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If you have a water pump you should connect it to CHA_FAN1 and change CHA_FAN1 to W_PUMP mode in the BIOS and the rear exhaust case fan to CHA_FAN2. ------------- AB350 Gaming-ITX/ac 10.50A BIOS | Ryzen 5 5600 | G.Skill Flare X 2x8GB @ 3466 14-14-14-28 1.4 V | Zotac RTX 5060 SOLO | Kingston KC3000 1 TB M.2 | SilentiumPC Supremo M2 550W | Thermaltake Core V1 |
Posted By: Granola6614
Date Posted: 28 Apr 2026 at 7:24pm
Hi, and thank you for your reply. However, I do not believe this is a solution. The CHA_FAN1 header does not work at all since the UEFI update, be it for a fan or for a water pump. What's more the "W_PUMP" mode is really useless IMHO since it runs the pump at full speed all the time, and my D5 PWM pump is much louder at full speed than at lower speeds (and my system really doesn't need a LOT of flow to stay cool). So I really need all 3 headers working in "fan" mode, none in "W_PUMP Mode". |
wino wrote:Posted By: Xaltar
Date Posted: 28 Apr 2026 at 7:51pm
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You can try opening a support ticket with ASRock and see if they can replicate your issue: http://tw.asrock.com/events/tsd.asp" rel="nofollow - http://tw.asrock.com/events/tsd.asp -------------
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Posted By: Granola6614
Date Posted: 29 Apr 2026 at 5:38pm
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Thank you I just did. In the meantime, I am investigating a little deeper : Please keep in mind this fan (BeQuiet Silent Wings 3 PWM 120mm) had been working on this CHA_FAN1 for years with no issue. I made sure it works properly when plugged into CPU_FAN, which made me think the problem was with the CHA_FAN1 header. However, I tested CHA_FAN1 today with another (smaller) PWM fan and it turned on and was detected on CHA_FAN1. So in short : the header seems to work, the fan seems to work, they have been working together for years but now they only work if not together?! LOL Do you have any suggestions as to how I could solve this issue? |
Posted By: Xaltar
Date Posted: 29 Apr 2026 at 6:10pm
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I'm at a loss I'm afraid. Aside from maybe swapping your AIO fans to CHA_FAN1 and using the bequiet fan on CHA_FAN2 or CPU_FAN1 (depending on your setup, just swap them). Seems a bit odd but I guess it's possible the header voltage output/PWM management was altered in the new BIOS making it incompatible with the fan. All just guesswork though. -------------
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Posted By: wino
Date Posted: 29 Apr 2026 at 6:25pm
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The CHA_FAN1 header works - that's a fact :) The other fan connected to it works and the water pump connected to it also works: "What's more, the "W_PUMP" mode is IMHO really useless because it pumps at full speed all the time" - these are your words ;) So I suggest connecting the water pump to CHA_FAN1 with CHA_FAN1 mode (not W_PUMP due to your preference) and the BeQuiet Silent Wings 3 fan to CHA_FAN2. If this does not help - try other settings (silent mode, full speed mode, customize mode, etc.) because everything indicates that the connector is working properly. You can also try connecting one fan at a time to find the cause. ------------- AB350 Gaming-ITX/ac 10.50A BIOS | Ryzen 5 5600 | G.Skill Flare X 2x8GB @ 3466 14-14-14-28 1.4 V | Zotac RTX 5060 SOLO | Kingston KC3000 1 TB M.2 | SilentiumPC Supremo M2 550W | Thermaltake Core V1 |
Posted By: Granola6614
Date Posted: 29 Apr 2026 at 11:57pm
Thank you very much for your message. While your suggestion to connect my water pump to CHA_FAN1 is a good idea (although not easy for me because of how difficult CHA_FAN2 is to get to since I have installed a full motherboard waterblock), I would like to share a finding I just made which seems very odd to me : So my motherboard is set to PWM Mode for CPU_FAN and for CHA_FAN1. However, I pulled my multemeter and measured : 12V between the yellow and the black wire of a fan on CPU_FAN Only 5.85V (let's call it 6V) between the same wires of the same fan when I connect it to CHA_FAN1. That seems really weird to me, and makes me think my motherboard is perhaps kind of mixing PWM and DC modes... What do you think? |
Posted By: wino
Date Posted: 30 Apr 2026 at 1:23am
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Hmm, something's really wrong here. I checked the voltage in CPU_FAN, CHA_FAN1 and CHA_FAN2 with a multimeter. In CPU_FAN and CHA_FAN2 the voltage between PIN1 and PIN2 (I don't know the colors, because they are all black) is 12V. However in the case of CHA_FAN1 it is only 5.95V - both in PWM and DC mode. ------------- AB350 Gaming-ITX/ac 10.50A BIOS | Ryzen 5 5600 | G.Skill Flare X 2x8GB @ 3466 14-14-14-28 1.4 V | Zotac RTX 5060 SOLO | Kingston KC3000 1 TB M.2 | SilentiumPC Supremo M2 550W | Thermaltake Core V1 |
Posted By: wino
Date Posted: 30 Apr 2026 at 1:40am
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Okay, I tried different settings and here are the conclusions :) When I set the maximum power on CHA_FAN1, the voltage increases to 12V. Previously, I had it set to 40%, so the voltage was only 6V. I always thought that in the case of 4-pin fans, the 4th pin is responsible for controlling the fan speed. It seems that (at least on our motherboard) the speed is controlled by the voltage applied to pin 2. ------------- AB350 Gaming-ITX/ac 10.50A BIOS | Ryzen 5 5600 | G.Skill Flare X 2x8GB @ 3466 14-14-14-28 1.4 V | Zotac RTX 5060 SOLO | Kingston KC3000 1 TB M.2 | SilentiumPC Supremo M2 550W | Thermaltake Core V1 |
Posted By: Granola6614
Date Posted: 30 Apr 2026 at 1:41am
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Aha! Thank you so much for having tested as well! So this points in the direction of something being wrong not only with my motherboard but more broadly, perhaps this comes from the UEFI code. It's kind of as if we were using PWM and DC modes at the same time on CHA_FAN1, whereas the two other fan headers work properly. I don't know how we could notify ASRock about our similar findings for them to investigate further. |
Posted By: Granola6614
Date Posted: 30 Apr 2026 at 1:44am
I think you are correct in thinking that in PWM mode the voltage sent to the fan should always be 12V, and the modulation is made through the signal sent through the 4th pin. So to me our measurements of around only 6 volts between the 2 first pins is a problem: it corresponds to a speed reduction in DC mode, but should not occur in PWM mode. |
Posted By: wino
Date Posted: 30 Apr 2026 at 2:07am
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It seems to me that this is not a bug. CPU_FAN and CHA_FAN2 are headers intended only for PWM (4-PIN) fans. The CHA_FAN1 header is designed for both types of fans - PWM (4-PIN) and DC (3-PIN). That?™s why its behavior is different. Yes, 4-PIN fans will work here, even in PWM mode, but in this case it?™s probably some kind of "legacy" mode. That?™s why, regardless of which mode we set (DC or PWM), the speed is controlled by voltage. Apparently, it can?™t be done any other way if we want a header that can operate in both modes. ------------- AB350 Gaming-ITX/ac 10.50A BIOS | Ryzen 5 5600 | G.Skill Flare X 2x8GB @ 3466 14-14-14-28 1.4 V | Zotac RTX 5060 SOLO | Kingston KC3000 1 TB M.2 | SilentiumPC Supremo M2 550W | Thermaltake Core V1 |
Posted By: Granola6614
Date Posted: 30 Apr 2026 at 2:51am
I don't see why : set the voltage to 12V and activate the 4th pin with the modulation signal for PWM Mode, or do not activate the 4th pin and modulate the voltage on pin 2 for DC mode. That seems quite straightforward to me. |
Posted By: wino
Date Posted: 30 Apr 2026 at 3:57am
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I don?™t know, that?™s the only thing I could think of ;) If you've already reported the issue to ASRock support, you might want to mention that the voltage issue isn't unique to you. It's possible it's a BIOS error. ------------- AB350 Gaming-ITX/ac 10.50A BIOS | Ryzen 5 5600 | G.Skill Flare X 2x8GB @ 3466 14-14-14-28 1.4 V | Zotac RTX 5060 SOLO | Kingston KC3000 1 TB M.2 | SilentiumPC Supremo M2 550W | Thermaltake Core V1 |
Posted By: Xaltar
Date Posted: 30 Apr 2026 at 4:18am
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Better yet, point ASRock Tech Support to this thread so they can see everything you have both tried. Good luck  -------------
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Posted By: Granola6614
Date Posted: 02 May 2026 at 12:21am
Hi, I did it yesterday. I hope they will follow-up. |
Posted By: Granola6614
Date Posted: 05 May 2026 at 2:00am
Hi Wino, I just wanted to let you know that ASRock sent me a modified version of the latest UEFI (they named the file V10.50A) and it has solved the issue on my motherboard. Now the CHA_FAN1 header works properly in PWM mode, and I measured 12 volts on the second pin of this header. The other fan headers also work fine. Let me know if you want me to send this file to you, or you can ask it directly to ASRock. |
Posted By: Xaltar
Date Posted: 05 May 2026 at 6:10am
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Awesome, glad to hear it. I suspect ASRock will likely include the fix in the next BIOS update, probably fairly soon. Thanks for bringing it to their attention -------------
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Posted By: wino
Date Posted: 05 May 2026 at 5:03pm
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@Granola6614: Great news :) So it was a BIOS bug after all. I'll contact them to make sure this update isn't designed specifically for your build. @Xaltar: Do you think there will be another BIOS update? This motherboard is almost 10 years old... ------------- AB350 Gaming-ITX/ac 10.50A BIOS | Ryzen 5 5600 | G.Skill Flare X 2x8GB @ 3466 14-14-14-28 1.4 V | Zotac RTX 5060 SOLO | Kingston KC3000 1 TB M.2 | SilentiumPC Supremo M2 550W | Thermaltake Core V1 |
Posted By: Xaltar
Date Posted: 05 May 2026 at 5:19pm
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It's possible, particularly with the RAM shortage and AMD rereleasing some older AM4 CPUs. Who can say for sure. -------------
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Posted By: wino
Date Posted: 10 May 2026 at 1:29am
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I contacted ASRock and they sent me 10.50A version. It even appeared on the official motherboard website ;) ------------- AB350 Gaming-ITX/ac 10.50A BIOS | Ryzen 5 5600 | G.Skill Flare X 2x8GB @ 3466 14-14-14-28 1.4 V | Zotac RTX 5060 SOLO | Kingston KC3000 1 TB M.2 | SilentiumPC Supremo M2 550W | Thermaltake Core V1 |
Posted By: Xaltar
Date Posted: 10 May 2026 at 5:39am
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Excellent, that is good to hear. Thanks for the info. -------------
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Posted By: Granola6614
Date Posted: 11 May 2026 at 1:23am
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I am really glad we diagnosed this all together and ASRock's Technical Support team was so responsive. To be honest I was not expecting such a large company to move this fast and to listen so well to customer feedback. 5/5 stars to ASRock for this. |