CPU Fan Stuck at Max / Fluctuating – Nitro ANV15-51 BIOS v1.26

Hi, I’m experiencing a recurring fan control issue on my Acer Nitro V15 ANV15-51, currently running BIOS version V1.26 (Insyde Corp., 2025-03-21).

The problem:

The CPU fan runs at full speed constantly, even when the system is idle and cool.
Sometimes, the fan fluctuates rapidly, going from high to low speed every few seconds.
Other times, the issue doesn’t occur at all.
NitroSense fan settings are ignored or overridden.
The GPU fan works perfectly fine — this only affects the CPU fan.

What I’ve already tried:

EC reset via battery pinhole
CPU limited to 50% in Power Optionss
Had the laptop cleaned
Sent to an Acer service center (no hardware issues found)

Even after all this, the issue still randomly comes and goes.

Additional Info:

CPU temps are normal (30–50°C) when the fan ramps up
This seems to be a firmware-level bug related to BIOS v1.26
Other users with the same model and BIOS are experiencing the same issue

Please confirm if a fix is planned (e.g., BIOS v1.27 or EC patch).
This issue is affecting normal use of the device.

Thanks in advance.

Also, BIOS v1.26 updates EC version, and this might be the reason why.

Accepted answers

All comments

Puraw

https://community.acer.com/en/discussion/727095/cpu-fan-stuck-at-max-fluctuating-nitro-anv15-51-bios-v1-26

Hi Munchkin 👋

You're not alone—this fan issue has been popping up on several ANV15-51 units running BIOS v1.26. It seems tied to how the EC update handles power boosts and thermal states.

🛠️ Here's what tends to help:

Disable “Performance Boost” under Advanced Power Settings > Processor power management. This reduces unnecessary CPU ramping at low workloads (see picture).
Don’t limit max CPU power to 50%—that can throttle performance without resolving fan control.
Switch to “Best Power Efficiency” mode in System > Power & Battery settings. It balances thermal behavior better across workloads.

These steps usually stabilize fan fluctuations without needing deep firmware tweaks. If things persist, there might be BIOS v1.27 on the horizon to patch EC behavior 🤞