MB Asus Zenbook UX31A cannot control fan and is always at max spin

[Dimi_01]

Hello, I ve been using many Asus Zenbooks UX31A over the past 7 years.
I bought 1 for me, 2 more for my family.
Another 2-3 I bought repaired & sold.

Recently I bought a new MB from a big Chinese seller, selling refurb MBs with factory warranty.
I chose 8GB ram, an upgrade for myself.
So I tested the new MB. All appaered OK, except it cannot control the FAN speed. It is always at max making constant noise.

I am testing 2 identical UX31A. With all combinations only the defective MB has the problem.

1. BIOS test: Tried with 218 and 219, both latest BIOS of asus zenbook UX31A.
no setting inside for fan control.
2. FAN test: Tried with 2 properly working fans. Only with faulty MB they fail
3. Windows test: Tried with 2SSDs with diff windows OS. Only with faulty MB they failAlso happens at power on when no OS is installed.
4. No dust, no heat. CPUs are at 40 deg Celsius.

HW utilities show:
1.Proper temp reporting of CPU & GPU
2. FAN 3300 RPM with good MB, 25500 RPM with bad MB.
Seller offered me 8$ discount for this problem which is ridiculous. I want it either fixed or returned.
But Ill have to send it back to China.

So any idea for an easy fix?

 

[romirez]

Use fan speed reducer for laptop OR rework microchip/smd components.

 

[webworkings]

It is also possible that the fan is bad/going bad and needs replacing.

 

[romirez]

It is also possible that the fan is bad/going bad and needs replacing.

Tried with 2 properly working fans. Only with faulty MB they fail

 

[Dimi_01]

I sent the MB back to the seller. He promised a replacement after me describing the problem. Now Ill wait around a month and test the new MB that comes.

 

[wpp]

You upgraded the motherboard. The fan model changes with that motherboard. The old model fan will run at 100% if you use it on the newer motherboard.