cpu fan connection

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johngey158402e0

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Can the cpu cooler (fan) be plugged into one of the "sys fan" terminals on the motherboard? I have a case that has a plug for the cpu fan terminal to control the speed of the other fans (I think). In other words, if I plug the cpu fan into a sys_fan port, will the motherboard know how to moderate the speed to keep it cool?
 
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Hi,

No, you shouldn't plug the CPU cooler into a SYS_FAN header. The CPU_FAN header is designed to control the cooler based on CPU temperature, while SYS_FAN headers adjust speeds based on general system temps. If the CPU fan isn't detected on CPU_FAN, your system might show an error or even refuse to boot. If your case has a fan hub that connects to CPU_FAN, check the manual - it might have a separate connector for the CPU cooler itself. Always plug the CPU cooler into CPU_FAN to ensure proper cooling.
 
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johngey158402e0 said:
Can the cpu cooler (fan) be plugged into one of the "sys fan" terminals on the motherboard? I have a case that has a plug for the cpu fan terminal to control the speed of the other fans (I think). In other words, if I plug the cpu fan into a sys_fan port, will the motherboard know how to moderate the speed to keep it cool?
Click to expand...

The question is based on the false assumption that the case's fan control is somehow superior to the board's own fan control. But in reality, you should connect every fan directly to the board's headers and let the board control them via fan curves, see my Guide: How to set up a fan curve in the BIOS. Once you set this up properly, there is no reason for the case to control anything, let alone operate some switch on the case where you can change the fan speeds manually or something. Nowadays, let the fan curves do their job, you only have to set it up once.

The CPU fan, i'd put on CPU_FAN, but not because the SYS_FAN headers cannot operate off of the CPU temperature or anything, but simply because it then shows up in monitoring software as the CPU fan it is, and also, yes, the board can have a "fan fail" warning for the CPU fan, should it not work anymore one day.
 
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kow10fdb026e said:
The CPU_FAN header is designed to control the cooler based on CPU temperature, while SYS_FAN headers adjust speeds based on general system temps.
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Wrong. In the BIOS you can configure what temperature source should control the speed of each FAN header.

kow10fdb026e said:
If the CPU fan isn't detected on CPU_FAN, your system might show an error or even refuse to boot.
Click to expand...
Wrong again. There are people who have a 100% passively cooled system with not a single fan, and they boot just fine.
Other users have a fan controller which is fully separated from the mainboard, where the BIOS does not see the fan speeds and again, they boot fine.

Have you created your new user account just to spread misinformation?
 
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Let's not be too harsh if someone posts something that's not quite accurate, we can easily correct it in a factual matter. Heck, i think i sometimes come across as unfriendly when i correct stuff, but we don't have to then also insinuate that there's an agenda behind the inaccuracy. I'm sure he meant well, he was slightly off the mark, but if we come down too hard on him, he might hesitate to help again, if he were to have the solution to something.
 
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MadSky said:
Wrong. In the BIOS you can configure what temperature source should control the speed of each FAN header.
Click to expand...
You're right that in the BIOS, you can change the temperature source for SYS_FAN, but by default, these headers are controlled by overall system temperature, not the CPU. Most users never touch those settings, so plugging a CPU cooler into SYS_FAN without configuring it is just asking for overheating.

MadSky said:
Wrong again. There are people who have a 100% passively cooled system with not a single fan, and they boot just fine.
Other users have a fan controller which is fully separated from the mainboard, where the BIOS does not see the fan speeds and again, they boot fine.
Click to expand...
Sure, passive cooling exists—brilliant observation! But that doesn’t magically stop motherboards from checking CPU_FAN. Many will still throw errors or refuse to boot unless you disable the failsafe.

MadSky said:
Have you created your new user account just to spread misinformation?
Click to expand...
Before you start throwing around accusations of ‘misinformation,’ maybe ask yourself if you’re actually providing useful advice - or just trying to sound smarter than you are.
 
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kow10fdb026e said:
You're right that in the BIOS, you can change the temperature source for SYS_FAN, but by default, these headers are controlled by overall system temperature, not the CPU. Most users never touch those settings, so plugging a CPU cooler into SYS_FAN without configuring it is just asking for overheating.
Click to expand...
On MSI AMD AM5 BIOS all FAN headers default to CPU core.
For older boards or for other brands it might be different.

Why are you telling the user that they should not do it, if it actually can be done?
The user came to this forum and is asking for support but you are basically telling them that they better stop doing whatever they intend to do as if there is no way.

kow10fdb026e said:
Sure, passive cooling exists—brilliant observation! But that doesn’t magically stop motherboards from checking CPU_FAN. Many will still throw errors or refuse to boot unless you disable the failsafe.
Click to expand...
On MSI AMD AM5 BIOS there is no such thing. Magic! 🌟
For older boards or for other brands it might be different.

kow10fdb026e said:
Before you start throwing around accusations of ‘misinformation,’ maybe ask yourself if you’re actually providing useful advice - or just trying to sound smarter than you are.
Click to expand...
I am correcting your half-truths so other users, who come across this thread, will know that they have the option to configure their system to their liking. You are welcome.
 
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Its Important to always Connect a CPU Fan or PUMP to the CPU Fan or PUMP Header as the Computer Monitors them headers for a Tachometer Signal to make sure at least one is Spinning and if it is not it will refuse to POST with a Warning of CPU FAN FAILURE or PUMP FAILURE and refuse to go any Further as no fan being connected there Is sensed as a Failure and it thinks the CPU Fan has Failed so locks out the boot to prevent the CPU From Frying Itself.
 
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Arshrao129 said:
Yes, you can plug the CPU fan into a SYS_FAN header, but it is not recommended because system fan headers usually regulate speed based on overall system temperature rather than the CPU's specific thermal load, which can lead to improper cooling under heavy tasks.
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This sounds like something an AI chatbot would say. And it's false. All the headers default to CPU temperature.

He's a spammer anyway, like I reported a while back. A couple harmless-looking AI-generated posts under some old topics, then one with a spam link here.
 
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You don't have this button? I already reported it though.

Screenshot 2026-09-03 at 17-37-26 cpu fan connection MSI Global English Forum.png


When you click on the member, you can also report the member as a whole, instead of a specific post.
 
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citay said:
You don't have this button? I already reported it though.

View attachment 212549

When you click on the member, you can also report the member as a whole, instead of a specific post.
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I had noticed the user was removed by now. :-)

I see no report button. I checked with three browsers: Vivaldi (main browser), Firefox and Edge. They all do not show the Report button. Next step I disabled uBO adblocker and reloading the page which also did not bring the Report button.

I am bit puzzled why it is not there. It always surprised it was not there but never bothered to inquire until now. ;)

MSI forums no report button.png
 
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On the user page, it would be way on the right (I made the window a bit narrower here):

Screenshot 2026-09-03 at 19-48-58 ericj159802e9 MSI Global English Forum.png


Don't know why it's not there for you. I use FF with uBO.

In the other browsers, you logged in though, right?
 
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The plot thickens. I was logged in on all browsers. I made another screenshot like you did with a narrower view. Still the Report button does not show.

I have one hypothesis left and that would be that the button is not avaible for regular members but only for Sergeants, Global Moderators and admins? It stumps me. 🙃
 
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