Question 3-pin case fan controller question

Pollin

Honorable
Oct 22, 2013
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Hello, everyone!

I have an old(ish) MSI 970a-g43 motherboard which I bought long before I had any real understanding of good PC builds. I recently discovered, while trying to replace some case fans and add some extra ones, that of the two SYS_FAN headers on the board, one is 3-pin but with only a ground and +12v pin, the other pin is decoration, and the other is a 4-pin, but uses the standard 3-pin layout with the fourth pin again not actually doing anything.

I have six case fans, all 3-pin fans. Three of these are currently plugged into a splitter cable on the one header that works as a 3-pin header. The other 3 are currently disconnected as plugging them into the 2-pin header makes them run at 100% power which makes them obnoxiously loud.

Are there any good 3-pin fan controllers that will allow me to properly control my case fans? I looked around and found one or two that might work but I'd like to hear recommendations from someone more experienced than I am with this. I'd really rather not replace the motherboard if I don't have to, since it's just for some extra, nonessential cooling fans.

Edit: I'm currently looking at this controller:
https://www.amazon.com/AeroCool-Touch-Temperature-Controller-Cooltouch/dp/B00GMYATYK/ref=sr_1_13?dchild=1&keywords=fan+controller&qid=1589165469&s=electronics&sr=1-13

It's fairly cheap but has decent reviews and uses molex power so I don't have to connect it to the motherboard. I figure I can run four of my fans off that and the other two off the splitter cable on the 3-pin header. If anyone has any alternatives or advice, I'd love to hear it.
 
Last edited:

Paperdoc

Glorious
Ambassador
Your understanding of what your mobo SYS_FAN headers do is quite correct, so most fan Hubs will NOT work for you because they only work on 4-pin fan systems. Luckily, there is a new product coming on the market by Phanteks that does what you need. This seller says they expect to have it by the end of May/20.

https://www.amazon.com/Phanteks-Universal-Fan-Controller-PH-PWHUB_02/dp/B07NHQRCRM/ref=sr_1_2?dchild=1&keywords=Phanteks+fan+hub&qid=1589164376&sr=8-2

This Hub, like all others, gets power from a SATA power output connector from your PSU, and draws no power from your mobo header, so you avoid the current limit of that header. But it has two unique features not found in other Hubs. First, it has both 4-pin PWM Mode output headers (4 of them) and 3-pin DC Mode output headers (3 of them), the latter suited to your need. Secondly, it can accept input signals for control of fan speed EITHER from a 4-pin header using the new PWM Mode, OR from a 3-pin header using the older Voltage Control Mode (aka DC Mode). It comes with the cable required to connect to that SATA output, with a small manual speed control box (YOU do not need to use) and with a cable to connect to your mobo's SYS_FAN1 header that does output standard 3-pin fan signals.

Then your only issue is how to connect 6 case fans to three 3-pin output ports. You simply get three common Splitters that each let you connect two fans to one port. To be sure the Splitters will fit into the small opening around each 3-pin port, get only 3-pin Splitters. Although Phanteks' website does not give a spec for the max current output of each single port, it does say the unit's max output is 48 W, which means 4 A total for ALL fans connected. Almost all simple 3-pin fans now draw max current in the range 0.07 to 0.25 A, so no problem there.

One small item FYI. All Hubs send back to their host fan header the speed from only ONE of their fans becasue of the limitations of the header's pulse counting system. This Hub does that for the fan plugged into port #1 (white), which is 4-pin. I suspect if you do NOT plug any fan into that port (and you should not with only 3-pin fans), the SYS_FAN1 header may get no fan speed signal and MAY send you an alarm of a failed case fan. If that happens, look in BIOS Setup for the SYS_FAN1 header and see if you can disable that alarm or ignore the fan speed for it. The header does NOT need to know that speed to do its control work; it is really only used for display and for monitoring the fan for failure.
 

Pollin

Honorable
Oct 22, 2013
32
0
10,530
0
Your understanding of what your mobo SYS_FAN headers do is quite correct, so most fan Hubs will NOT work for you because they only work on 4-pin fan systems. Luckily, there is a new product coming on the market by Phanteks that does what you need. This seller says they expect to have it by the end of May/20.

https://www.amazon.com/Phanteks-Universal-Fan-Controller-PH-PWHUB_02/dp/B07NHQRCRM/ref=sr_1_2?dchild=1&keywords=Phanteks+fan+hub&qid=1589164376&sr=8-2

This Hub, like all others, gets power from a SATA power output connector from your PSU, and draws no power from your mobo header, so you avoid the current limit of that header. But it has two unique features not found in other Hubs. First, it has both 4-pin PWM Mode output headers (4 of them) and 3-pin DC Mode output headers (3 of them), the latter suited to your need. Secondly, it can accept input signals for control of fan speed EITHER from a 4-pin header using the new PWM Mode, OR from a 3-pin header using the older Voltage Control Mode (aka DC Mode). It comes with the cable required to connect to that SATA output, with a small manual speed control box (YOU do not need to use) and with a cable to connect to your mobo's SYS_FAN1 header that does output standard 3-pin fan signals.

Then your only issue is how to connect 6 case fans to three 3-pin output ports. You simply get three common Splitters that each let you connect two fans to one port. To be sure the Splitters will fit into the small opening around each 3-pin port, get only 3-pin Splitters. Although Phanteks' website does not give a spec for the max current output of each single port, it does say the unit's max output is 48 W, which means 4 A total for ALL fans connected. Almost all simple 3-pin fans now draw max current in the range 0.07 to 0.25 A, so no problem there.

One small item FYI. All Hubs send back to their host fan header the speed from only ONE of their fans becasue of the limitations of the header's pulse counting system. This Hub does that for the fan plugged into port #1 (white), which is 4-pin. I suspect if you do NOT plug any fan into that port (and you should not with only 3-pin fans), the SYS_FAN1 header may get no fan speed signal and MAY send you an alarm of a failed case fan. If that happens, look in BIOS Setup for the SYS_FAN1 header and see if you can disable that alarm or ignore the fan speed for it. The header does NOT need to know that speed to do its control work; it is really only used for display and for monitoring the fan for failure.
Interesting, thank you. I'm not enamored with having to buy yet more splitters since the ones I do have are four pin, but I'll keep that hub in mind. Though estimated time of delivery is over a month for me so I'm going to keep looking until I'm sure there's no other (and faster) options.
 

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