https://forum.asrock.com/ Copyright (c) 2006-2013 Web Wiz Forums - All Rights Reserved. Mon, 13 Apr 2026 01:39:12 +0000 Fri, 13 Jun 2025 09:05:46 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.04 360 https://forum.asrock.com/RSS_post_feed.asp?TID=110989 https://forum.asrock.com/forum_images/web_wiz_forums_black.png https://forum.asrock.com/ https://forum.asrock.com/forum_posts.asp?TID=110989&PID=195949&title=chassis-fan-stuck-at-100#195949 Author: Kuenec
Subject: 110989
Posted: 13 Jun 2025 at 9:05am

I?™m using an ASRock B650M PG Lightning WiFi 6E and I?™m experiencing a fan control issue that began immediately after updating to BIOS version 3.25.

Before updating, my 4-pin PWM fans connected to CHA_FAN1 and CHA_FAN2 worked perfectly and followed the fan curves set in BIOS. However, after updating to version 3.25:

??Fans connected to CHA_FAN1 and CHA_FAN2 now run at maximum speed constantly, regardless of the BIOS fan curve settings.

??The fans do respond when I change their settings in BIOS (they briefly shut off while the other fans connected to CHA_FAN3 run) but they do not follow the fan curve and return to 100% speed.

??When I plug those same fans into CHA_FAN3, they work perfectly, they follow the BIOS fan curve as expected and behave normally.

To try and fix the issue, I?™ve already:

??Verified all fans are 4-pin PWM
??Manually set the headers to PWM mode in BIOS under the H/W Monitor tab
??Tried multiple fan curve profiles: Standard, Silent, and Custom
??Removed the CMOS battery to reset all BIOS settings
??Flashed back to the original BIOS version that came with the board but the problem still persists, even on the older BIOS
??Swapped fans across all headers to verify the fans themselves are functioning properly

This leads me to believe there may be a firmware issue introduced by BIOS 3.25 that affected CHA_FAN1 and CHA_FAN2 behavior especially since CHA_FAN3 continues to function correctly with the exact same fans.

Motherboard Model: ASRock B650M PG Lightning WiFi 6E

BIOS Version: 3.25

I?™d really appreciate your help determining whether this is a known issue or if there?™s a workaround or fix available.]]> Fri, 13 Jun 2025 09:05:46 +0000 https://forum.asrock.com/forum_posts.asp?TID=110989&PID=195949&title=chassis-fan-stuck-at-100#195949