Question Systems Fan confusion

ptTimeBldr

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Nov 13, 2022
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My mobo has two different types of socket for systems fans as outlined or indicted. Why are there two different connectors both called 'SYS_FAN' and which one is normally used? The one near the front USB or the one near the TPM?
 

Darkbreeze

Retired Mod
Your board has three fan headers. One is the CPU fan header, two are system fan headers. ALL of the headers on this board are exactly the same being PWM 4 pin headers with pin 1 being GND, pin 2 being voltage speed control, pin 3 being the sense pin and pin 4 being PWM speed control.

All three headers on this board allow you to choose between normal, silent, full speed or a manually controlled custom fan curve which you can configure in the Smart Fan 5 section of the BIOS.

All three headers on this board allow you to choose WHICH thermal sensor to use for the temperature control input, so that you can specify for example that the CPU fan uses the CPU thermal sensor and that the other two use the motherboard thermal sensor (Usually recommended) or something else like the GPU thermal sensor, VRM sensor, etc.

All three headers allow you to control what type of control they use, by setting each header to either Auto, voltage controlled (For DC 3 pin controlled fans) or PWM (For PWM 4 pin controlled fans).


I realize that fan header LOOKS different than the CPU fan and the other Sys Fan header, but based on the manual it does not specify there being any difference for that fan even though I can look at actual pictures of that board and tell that that header looks different. You may wish to contact Gigabyte and ask for clarification as it would definitely not be the first time I've found discrepancies in motherboard user manuals.
 

ptTimeBldr

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Nov 13, 2022
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Thanks again. I know about the cpu fan and I realise there's two system fan headers, but I agree with you that they don't look the same. They have the same number of pins, but they're spaced differently, both on the diagram and the mobo itself. I've ordered an 8cm fan that will connect to one or the other, hopefully the one next to the front USB header as I want it mounted near the front of the mobo so as to cool the memory modules.
Thanks for saying that that the CPU fan uses the CPU thermal sensor and that the other two use the motherboard thermal sensor, this will be useful come the time.
 

Darkbreeze

Retired Mod
The one that is the same as the CPU fan header is the normal one, and the one you should use as this is what all standard fans are going to have connectors to match. The other one, can you take a really good picture of it with decent lighting that is close enough to see details of the socket and pin structure and post that here. I will take a look and also see if I can get @Paperdoc to chime in as he has far more experience in this area than just about anybody else around here so it may be that he knows why it's different, why the manual does not say it is different and wth it is actually for.



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ptTimeBldr

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Nov 13, 2022
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The one that is the same as the CPU fan header is the normal one, and the one you should use as this is what all standard fans are going to have connectors to match. The other one, can you take a really good picture of it with decent lighting that is close enough to see details of the socket and pin structure and post that here. I will take a look and also see if I can get @Paperdoc to chime in as he has far more experience in this area than just about anybody else around here so it may be that he knows why it's different, why the manual does not say it is different and wth it is actually for.



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Many thanks again. Yep, I was thinking that the one that's the same as the CPU fan header was the more usual one, but I wasn't certain, so thanks for clearing that up. Right, just getting that pic done...

The image isn't that great (samsung phone camera isn't that good) but you can still see the pins, and the cable is the one that came with the open frame case that is for a systems fan and definitely goes into that socket.
 
Last edited:

Paperdoc

Polypheme
Ambassador
This MAY be simple. It appears from the mobo manual that they have used on odd mobo fan header for SYS_FAN2, PLUS supplied an "Extension Cable" That cable you plug in there so that you DO get a standard male fan connector at the other end of this cable. You have shown that Extension Cable in your last photos. BUT there's an oddity in that. The male output connector has a small "tongue" on one side with an open gap beside it. That is how a standard male fan connector is designed, and the female connector from the fan has little ridges down one side so you can only plug in one way. HOWEVER, in your photo the tongue is off-centre in wrong direction so that it would not allow you to plug in a fan. Is it possible your photo was reversed and the tongue is really offset to the other direction? Can you actually plug a normal fan into the end of that Extension Cable?
 
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ptTimeBldr

Great
Nov 13, 2022
131
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This MAY be simple. It appears from the mobo manual that they have used on odd mobo fan header for SYS_FAN2, PLUS supplied an "Extension Cable" That cable you plug in there so that you DO get a standard male fan connector at the other end of this cable. You have shown that Extension Cable in your last photos. BUT there's an oddity in that. The male output connector has a small "tongue" on one side with an open gap beside it. That is how a standard male fan connector is designed, and the female connector from the fan has little ridges down one side so you can only plug in one way. HOWEVER, in your photo the tongue is off-centre in wrong direction so that it would not allow you to plug in a fan. Is it possible your photo was reversed and the tongue is really offset to the other direction? Can you actually plug a normal fan into the end of that Extension Cable?
Yes, it seems I made a slight misrepresentation. That systems fan cable did in fact come with the motherboard and not the open frame chassis. Anyway, the plug end certainly goes into the fan header next to the TPM pins, and the other end connects to a normal fan (I did a test-fit with the fan supplied with the AMD cooler that would also plug into the CPU fan header).
 

Darkbreeze

Retired Mod
It's because some of Gigabytes mini-ITX boards are used in All In One PCs that have proprietary fans using that other connector, from what I can discern. Why they didn't simply make them standard headers and require the AIO to use an adapter cable, who knows. I don't understand why these technology companies do a lot of the things they do BUT it's likely because that board gets used MORE in those AIO systems than what gets purchased by average consumers.
 
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ptTimeBldr

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Nov 13, 2022
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Right, so for the motherboard I have, Gigabyte is allowing for sys fans with both types of header connectors. That sort of makes sense, and at least now I know either fan type will work.
 

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