Asus UX51VZA fans always full speed

[EnricoS92]

Hi,

Before opening this thread I read all the topics I could find on this forum about similar problems.

I have an Asus Zenbook UX51V with a faulty mainboard (internally shorted PCH and ITE) and so I bought a used replacement board.

Everything is working fine, Windows loads without problems, all drivers are installed and every device is working fine, except both fans are spinning all the time at full speed as soon as I turn on the laptop.

In Windows, using HWMonitor temps are normal and if I stop the fans with my fingers temps do not rise suddenly (new thermal paste applied and heatpipe is making a good contact with both CPU, GPU and PCH).

What I tried so far, based on my researches:
- Installed Notebook Fan Control but it is not able to control the fan speed even if this notebook is fully supported;
- Installed SpeedFan, shows cpu fan speed over 5700 rpm and if I slow down the fan with my finger the reading decreases accordingly;
- Tried to update the bios with the Asus utility but it is already the latest version (v.204 is the latest for UX51VZA);
- Desoldered the BIOS chip and dumped, cleaned ME and reflashed, no change, everything is working but fans are always at full speed;
- Flashed with a BIOS dump (v.205 for UX51VZ) I found on this forum, no change;
- Flashed with the BIOS dump of my old faulty board, no change;
- Disconnected the LCD, keyboard, backlight etc., no change;

At this point I think that the problem is not the BIOS (including EC firmware and ME).
Any suggestion? If it is a simple fix I would like to avoid to contact the seller for a return/refund.

Attached the original bios dump from the new board with the fan speed problem and the boardview.

Thanks in advance.

[SMDFlea]

Re: Asus UX51VZA fans always full speed

I think its related to the EC. Force your bios to flash again, or downgrade to an earlier version.Version 2.07 is the latest i think ?
You can flash the bios by starting winflash from a command prompt. Navigate to the installed winflash directory, for example:

Type and enter:

cd C:\Program Files (x86)\ASUS\WinFlash

Then type and enter:

Winflash /nodate

Now you can update or downgrade your bios.

[jasko_jacker]

Re: Asus UX51VZA fans always full speed

Check pwm on fan connector, it's common on this model that the pin on ec is in short, check with multimeter. This line is connected directly with EC so an overcurrent can damage it. If the line isn't in short you can try to reprogramm bios (only with a programmer or with FPT if the descriptor allow it). (there is a small capacitor near fan connector check it)

[EnricoS92]

Re: Asus UX51VZA fans always full speed

I think its related to the EC. Force your bios to flash again, or downgrade to an earlier version.Version 2.07 is the latest i think ?
You can flash the bios by starting winflash from a command prompt. Navigate to the installed winflash directory, for example:

Type and enter:

cd C:\Program Files (x86)\ASUS\WinFlash

Then type and enter:

Winflash /nodate

Now you can update or downgrade your bios.

Hi,

thanks for the reply.

Version 207 is the latest on the asus website but I cannot flash it with the utility because it is for UX51VZH and mine is UX51VZA.

So I tried to downgrade from v.204 to v.203 using Winflash /nodate and flashed ok; now it powers on with fan full speed and doesn't POST anymore.
Tried a cmos reset without succes.

I'll have to desolder the bios chip tomorrow to put it in the programmer; I would like to try the 207 but I can't find a reliable working .bin online.

I can try to merge the file from the asus website (6 MB) with my dump. What do you think?

[EnricoS92]

Re: Asus UX51VZA fans always full speed

Check pwm on fan connector, it's common on this model that the pin on ec is in short, check with multimeter. This line is connected directly with EC so an overcurrent can damage it. If the line isn't in short you can try to reprogramm bios (only with a programmer or with FPT if the descriptor allow it). (there is a small capacitor near fan connector check it)

Hi,

thanks for the reply.

pwm pin and tach pin are ok, didn't find any short.

Both fans are OK, I tested them on another asus laptop.

FPT doesn't work on this laptop.

[SMDFlea]

Re: Asus UX51VZA fans always full speed

Hi,

thanks for the reply.

Version 207 is the latest on the asus website but I cannot flash it with the utility because it is for UX51VZH and mine is UX51VZA.

So I tried to downgrade from v.204 to v.203 using Winflash /nodate and flashed ok; now it powers on with fan full speed and doesn't POST anymore.
Tried a cmos reset without succes.

I'll have to desolder the bios chip tomorrow to put it in the programmer; I would like to try the 207 but I can't find a reliable working .bin online.

I can try to merge the file from the asus website (6 MB) with my dump. What do you think?

Yes, you can try merging the bios, also clean the ME .

[EnricoS92]

Re: Asus UX51VZA fans always full speed

Yes, you can try merging the bios, also clean the ME .

Ok I'll try it tomorrow and let you know.

[EnricoS92]

Re: Asus UX51VZA fans always full speed

Today I tried:
- Downloaded v.203 (for UX51VZA), merged with original dump and cleaned ME: powers on, doesn't post, fans always 100%
- Downloaded v.204 (for UX51VZA), merged with original dump and cleaned ME: everything works fine but fans 100%
- Downloaded v.207 (for UX51VZH), merged with original dump and cleaned ME: powers on, doesn't post, fans always 100%

Any hint?

[SMDFlea]

Re: Asus UX51VZA fans always full speed

Try this bios , if it doesn`t work i suggest to check the PWM fan area as suggested at post #3 .

EDIT: Bios moved https://www.badcaps.net/forum/showthread.php?p=1136113
.

[EnricoS92]

Re: Asus UX51VZA fans always full speed

Try this bios , if it doesn`t work i suggest to check the PWM fan area as suggested at post #3 .

Tried, powers on, doesn't post, fans always 100%.
I will reflash the original bios dump and check for something else.

[EnricoS92]

Re: Asus UX51VZA fans always full speed

Ok, I didn't solve the problem but I booted into Windows and noticed that the automatic brightness of the screen and of the KB backlight is not working.

I can see on the boardview that the SMB1_CLK_S and SMB1_DAT_S lines are shared between two temp sensors and the LCD.

Are these two lines also used to comunicate with the brightness sensor mounted on the screen?

If so this could be the problem

[jasko_jacker]

Re: Asus UX51VZA fans always full speed

Try to disconnect lcd and check the fan, On a ux31e when I disconnect the lcd the fan return ok so I remove a resistor near ec and "solve" the problem.

[EnricoS92]

Re: Asus UX51VZA fans always full speed

Try to disconnect lcd and check the fan, On a ux31e when I disconnect the lcd the fan return ok so I remove a resistor near ec and "solve" the problem.

Tried, no change.

[EnricoS92]

Re: Asus UX51VZA fans always full speed

Ok, solved.

Q2804 was faulty and was impeding the EC from reading the data of both the temperature sensors and the ambient light sensor.

Replacing it solved both the problems.

Thanks for the support.

[jcubed120]

Re: Asus UX51VZA fans always full speed

Hey EnricoS92,

I believe that my laptop may have this issue. Seeing as you've fixed your issue, would you be able to guide me through what's going on? I'd happily buy you a coffee or even a meal if you can help me sort this out.

I have the exact laptop you describe, and I think I may have the same issue. My question at the moment is, what is Q2804?

I'm a poor college student who was given this laptop and really can't afford a new one haha. Doing whatever I can to make it work but my ears are dying from the jet engine fans.

[EnricoS92]

Re: Asus UX51VZA fans always full speed

Hey EnricoS92,

I believe that my laptop may have this issue. Seeing as you've fixed your issue, would you be able to guide me through what's going on? I'd happily buy you a coffee or even a meal if you can help me sort this out.

I have the exact laptop you describe, and I think I may have the same issue. My question at the moment is, what is Q2804?

I'm a poor college student who was given this laptop and really can't afford a new one haha. Doing whatever I can to make it work but my ears are dying from the jet engine fans.

Hi,

Q2804 is responsible for both the temperature sensors and the ambient light sensor readings.

Your laptop should have the ambient light sensor for the automatic screen brightness compensation feature.

Boot into windows and check if it works by covering the sensor with your finger (I don't remember exactly where it is, usually near the webcam) and see if the brightness dims when you cover it and vice versa. (Check that all the drivers are installed)

If the automatic screen brightness compensation feature is working then Q2804 is fine.

Other causes to your problem are already described in this thread (BIOS, PWM signal and tach signal on fan connector etc.)

[ktmmotocross]

Re: Asus UX51VZA fans always full speed

u can isolate PWM signal and drive it by another voltage or u can even isolate its power pin and drive it from another voltage.

but u must check for temp for yourself

[s-r-h-n]

Re: Asus UX51VZA fans always full speed

Try to disconnect lcd and check the fan, On a ux31e when I disconnect the lcd the fan return ok so I remove a resistor near ec and "solve" the problem.

which resistor?