Question Can not control System Fan

Aug 27, 2020
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Hi, i have msi b450m-a pro max motherboard and can not control system fan speed. I can control cpu fan speed with smart fan but even if i reduce voltage on bios, case fans work at full speed. My previous mobo was gigabyte a320 and i could easily control all fans on gigabyte software. I installed msi dragon center and nothing changed. (case fans are 3 pins not pwm)

 
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(case fans are 3 pins not pwm)
Since your fans are three pin.... did you try setting the fan control to be 'voltage controlled' and not PWM controlled? Take it out of AUTO, if it has that option.

Also, for Ryzen 3000 CPU's it may seem you can't control fans as they tend to pulse a lot when the processor's at idle. It's really just low-energy temp spikes as the processor boosts but doesn't really get hot. What I advise is to set a flat fan curve that's a low, barely audible speed, up to about 65-70C then increase fan speed, only getting really loud at about 80-85C.
 
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Aug 27, 2020
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Since your fans are three pin.... did you try setting the fan control to be 'voltage controlled' and not PWM controlled? Take it out of AUTO, if it has that option.

Also, for Ryzen 3000 CPU's it may seem you can't control fans as they tend to pulse a lot when the processor's at idle. It's really just low-energy temp spikes as the processor boosts but doesn't really get hot. What I advise is to set a flat fan curve that's a low, barely audible speed, up to about 65-70C then increase fan speed, only getting really loud at about 80-85C.
Yes i tried both pwm and voltage options on bios. Nothing changed, still full speed. My cpu is ryzen 5 2600.
 
manual:
"CPU_FAN1, SYS_FAN1: Fan Connectors PWM Mode fan connectors provide constant 12V output and adjust fan speed with speed control signal. When you plug a 3-pin (Non-PWM) fan to a fan connector in PWM mode, the fan speed will always maintain at 100%, which might create a lot of noise. "

Couldn´t find any setting to alter in BIOS, but that´s the thing. Maybe you have to update the BIOS to a newer version.
 
Aug 27, 2020
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I tried both pwm and dc, temperature source cpu and system fans, smart fan mode on-off and set all voltage to lowest point but nothing changed.
 
Aug 27, 2020
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manual:
"CPU_FAN1, SYS_FAN1: Fan Connectors PWM Mode fan connectors provide constant 12V output and adjust fan speed with speed control signal. When you plug a 3-pin (Non-PWM) fan to a fan connector in PWM mode, the fan speed will always maintain at 100%, which might create a lot of noise. "

Couldn´t find any setting to alter in BIOS, but that´s the thing. Maybe you have to update the BIOS to a newer version.
I have the latest BIOS.
 
Aug 27, 2020
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That seems like an awful lot of fan wire bundles going to one header on what looks to be a 3- or 4-way splitter. How many fans do you have hooked to it? Have you tried just one fan all alone, no splitter, to see if it works right?
I tried every single fan without splitter one by one, still same, full speed. It is not about splitter because i used it with my previous mobo, there was no problem. I wrote to msi, maybe they can help.
 
I tried every single fan without splitter one by one, still same, full speed. It is not about splitter because i used it with my previous mobo, there was no problem. I wrote to msi, maybe they can help.
My concern would be the splitter allowed you to overload the controller on THIS motherboard with too many fans at once. I'm not at all sure it would, but maybe the overload simply damaged the controller's ability to adjust voltage to the fans which leaves it at a constant +12V.
 
Aug 27, 2020
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My concern would be the splitter allowed you to overload the controller on THIS motherboard with too many fans at once. I'm not at all sure it would, but maybe the overload simply damaged the controller's ability to adjust voltage to the fans which leaves it at a constant +12V.
Then why the same thing doesn't happen to a worse motherboard?
 
Then why the same thing doesn't happen to a worse motherboard?
Can't say for certain but it's quite possible it has a controller circuit that can handle the load.

Does your current motherboard have some other fan headers you could try using? Do it with ONE fan only and see if it can control it correctly. I'd not try the three-way splitter again though.

EDIT: naahh...i see all you've got is one sysfan and one cpufan header. the cpu fan almost certainly would control it so no sense in stealing that header.
 
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