Question AIO cooler speed change after BIOS update

Apr 19, 2022
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Hi!

My friend has an ASUS ROG strix Z390-H gaming board and a Cooler Master ML 240 RGB AOI-type CPU cooler.

The cooler is placed on the front panel with the pump cables on the top of the cooler segment.
Now the thing is that his MB works very weird and I suggested that most of his issues (Windows cannot start properly, etc.) could be a false BIOS update or some stuff so he updated BIOS using the Armory Crate.

Eversince the update the AOI cooler acts very awkward, it cranks up and down speed like constantly. CPU temp allegedly reaching heights like never before (75+ degrees) and no matter how he sets the curve for speed/temp it just seems to be totally random and out of the blue. CPU clockspeed also varies but I think this is Intel being in-and-out from TB (he has a 9900k, no OC).

Any ideas? Is that the cooler's fault? Is it an MB malfunction? Should we try to revert to prev. BIOS version?

Much appreciated!
 
Apr 19, 2022
6
1
15
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Worth mentioning that I have the same MB+Cooler combo (I have 9700k) and although I don't remember updating BIOS, but the cooler itself also acts rather weird on my end as well. At least sometimes. I circled it around by setting up a constant speed instead of curves so at least no annoying ups and downs. My rig is 2.5 yo and was never disassembled since, so cooling paste is 2,5 yo as well. He had a broken CPU 1,5 year ago so he fixed that then.
 

Paperdoc

Polypheme
Ambassador
I can suggest how a BIOS update MIGHT foul up an AIO system.

On that mobo the cable for the MOTOR part of the PUMP unit could have been plugged into any of three headers (see mobo manual, p. 1-16): CPU_FAN, CPU_OPT, or AIO_PUMP. The intent of the AIO system design is that the PUMP unit always should run full speed. Now, normally an AIO_PUMP header will ensure that happens. But if the pump is plugged into another header, its design tries to use a quirk of 4-pin fan designs. The PUMP unit is wired like a 3-pin fan, so when it is plugged into a header that is using the new 4-pin PWM Mode of fan control, that pump will do like an older 3-pin fan: it will always run full speed, and that is what we want. BEFORE the BIOS update the header where the pump was plugged in probably was configured to use the new PWM Mode. However, the UPDATE process may have caused that header to re-configure itself to the older DC Mode. IF that happened, then the pump would now behave like a fan t whose speed IS controlled according to the temperature inside the CPU chip and would constantly CHANGE its speed as CPU heat changes. BUT at the same time the RAD FANS also are changing their speeds in response to CPU temp, so the two items (pump and fans) fight each other and constantly speed up and slow down.

How to fix? CHECK exactly which mobo header the PUMP unit is plugged into. Now go into BIOS Setup and get to that header (see manual p. 3-7). For that particular header, ensure the MODE at upper right is set to PWM. Now also go to the header (SHOULD be the CPU_FAN or CPU_OPT header) where the RAD FANS are plugged in. That one ALSO should be set to PWM Mode since these fans ARE true 4-pin PWM design. This will ensure those fans are speed controlled properly. When done, use Esc to get back to Main Menu, then F10 to get to Exit Menu (p. 3-24). Choose SAVE Changes and Exit to save and reboot.

This should ensure the PUMP runs full speed all the time as designed, and all control of CPU cooling is done only changing the speed of the Rad Fans.
 
Reactions: Kuplungúr
Apr 19, 2022
6
1
15
0
I can suggest how a BIOS update MIGHT foul up an AIO system.

On that mobo the cable for the MOTOR part of the PUMP unit could have been plugged into any of three headers (see mobo manual, p. 1-16): CPU_FAN, CPU_OPT, or AIO_PUMP. The intent of the AIO system design is that the PUMP unit always should run full speed. Now, normally an AIO_PUMP header will ensure that happens. But if the pump is plugged into another header, its design tries to use a quirk of 4-pin fan designs. The PUMP unit is wired like a 3-pin fan, so when it is plugged into a header that is using the new 4-pin PWM Mode of fan control, that pump will do like an older 3-pin fan: it will always run full speed, and that is what we want. BEFORE the BIOS update the header where the pump was plugged in probably was configured to use the new PWM Mode. However, the UPDATE process may have caused that header to re-configure itself to the older DC Mode. IF that happened, then the pump would now behave like a fan t whose speed IS controlled according to the temperature inside the CPU chip and would constantly CHANGE its speed as CPU heat changes. BUT at the same time the RAD FANS also are changing their speeds in response to CPU temp, so the two items (pump and fans) fight each other and constantly speed up and slow down.

How to fix? CHECK exactly which mobo header the PUMP unit is plugged into. Now go into BIOS Setup and get to that header (see manual p. 3-7). For that particular header, ensure the MODE at upper right is set to PWM. Now also go to the header (SHOULD be the CPU_FAN or CPU_OPT header) where the RAD FANS are plugged in. That one ALSO should be set to PWM Mode since these fans ARE true 4-pin PWM design. This will ensure those fans are speed controlled properly. When done, use Esc to get back to Main Menu, then F10 to get to Exit Menu (p. 3-24). Choose SAVE Changes and Exit to save and reboot.

This should ensure the PUMP runs full speed all the time as designed, and all control of CPU cooling is done only changing the speed of the Rad Fans.
Hello Paperdoc! You make complete sense! The problem is that the AIO pump is certainly on the right header and although the header itself has 4 pins but you cannot go wrong with the 3pin connector due to a little bracket on it. So since it was fine before the BIOS update we assume that it causes some other stuff going on. We have checked the fan settings in BIOS and set most of them to PWM. Then in the AI Tweaker menu where you can set curves and RPSs in windows he can not toggle the "RPM fix mode" on in the top menu. I guess it doesnt really matter, although apparently one can also change the pump to follow a curve but in reality it is very likely that it can only work in constant rpm - as it should be.

Unfortunately no matter what he does or how he sets up fan curves and stuff in BIOS or in Windows, the speeds get all buggy and messed up after he runs even a not-very-demanding game like Valorant for example. But even if he opens Chrome or "This PC" the RPMs sometimes go medieval.
 

Paperdoc

Polypheme
Ambassador
If you are using ASUS' AI Suite / Tweaker to adjust your fan headers, be very careful about how it sets the header MODE for the PUMP. Many headers have an "AUTO" option for setting Mode, as well as PWM and DC. What AUTO does it TEST the fan connected by trying to change its speed using the PWM Mode. If that is NOT able to reduce the fan's speed, then it assumes it must be dealing with a 3-pin fan and changes its Mode setting to DC. Then it CAN and WILL change the speed of that fan. BUT if the "fan" is really your PUMP, it will disover that it keeps on running full speed in PWM Mode, change to DC mode, and start altering the pump's speed. That is exactly what we do NOT want! That is why I advised setting the header Mode to PWM specifically. Check to make sure AI Tweaker is not doing that change to DC Mode.
 

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