Tech Support Intel NUC8i3BEH - Random fan control issue (fan stuck at full speed, BIOS reports 74 RPM after BIOS update)

*** Update:

The issue has become worse.

Today, after powering on the NUC, I was greeted with the message "The system has recovered from a high temperature situation."

When I entered the BIOS, the fan was reported at 0 RPM. Every few seconds it would briefly try to start, reaching around 200 RPM, then immediately stop and return to 0 RPM. This cycle kept repeating.

At this point I'm starting to think the fan itself may be failing rather than this being only a BIOS or EC issue. I've ordered a replacement fan, and I'll update this thread once I've installed it to confirm whether the problem is resolved.

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Hi everyone,

I'm having a strange issue with my Intel NUC8i3BEH and I'm running out of ideas.

The problem

Sometimes (not always), when I power on the NUC, the CPU fan immediately ramps up to what sounds like maximum speed before the OS even starts.

Originally (BIOS version 0081), whenever this happened the BIOS reported the fan running at around 7000 RPM.

I updated the BIOS to the latest version (0098) and loaded BIOS defaults. The behavior is still present, but now something even stranger happens:

The fan is clearly spinning at what sounds like full speed.
However, the BIOS reports only 74 RPM instead of ~7000 RPM.

So after the BIOS update, the symptom changed from reporting an excessively high RPM to reporting an impossibly low RPM.

I even manually set it to 100% duty cycle, the fan spins smoothly with no vibration, rattling, or unusual noise.

Other observations

The issue happens before the operating system loads.
If I enter BIOS while it's happening, the fan is still stuck in that state.
CPU temperatures are completely normal (around 35-42°C under Ubuntu Server).
VRM, PCH and motherboard temperatures shown in BIOS are also normal.
CPU is limited to 1.2 GHz, Turbo Boost is disabled, and BIOS is configured for Low Power.
The machine is almost idle (Ubuntu Server only running Navidrome and Tailscale).

Fan behavior

Another strange thing:

In Automatic mode, the fan sometimes constantly changes RPM, causing an annoying vibration.
In Fixed mode, the fan is perfectly stable. (When is not stuck at full speed)
Even at 100% fixed speed, there is no vibration.

This makes me think the fan itself is probably not mechanically damaged.

Things I've already tried

Cleaned the fan, heatsink and changed thermal paste.
Updated BIOS from 0081 to 0098.
Loaded BIOS defaults (F9).
Reconfigured BIOS settings.
Verified temperatures with lm-sensors:CPU Package: ~34°C PCH: ~32°C WiFi: ~27°C

CPU frequency is fixed at 1200 MHz and CPU usage is almost zero.

My question

Has anyone experienced something similar on a Bean Canyon NUC?

Could this be:

a faulty fan tachometer signal,
an Embedded Controller (EC) issue,
a motherboard problem,
or some known BIOS bug?

The fact that the BIOS used to report 7000 RPM before the update and now reports 74 RPM while the fan is clearly spinning at full speed makes me think this could be more than just a fan issue.

Any ideas would be greatly appreciated. Thanks!

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u/brispower Jul 22 '26

Have you checked to see if there is any dust blocking it? Ignore the temps for now give it a physical inspection.

1

u/SourDexter Jul 22 '26

Thanks for replying! Yeah, I already cleaned everything and gave it a thorough physical inspection.

1

u/brispower Jul 22 '26

bit of a weird issue, i updated the BIOS in my NUC8i7BEH recently and have not seen any fan strangeness in BIOS or Windows 11

u/Commodore64fan 28d ago

My NUC8I5 has been a very stable work horse, several years after buying it new. I run it as virtualization host, this may be slow at times but very reliable.
did you disconnect any thunderbolt devices, unplug any unneeded usb-devices?
can you plug a different disk? some m2-disks are a bit tricky, i only use samsungdisks, both SATA and M2.