Asus AI suite Fan Xpert won't control the third chassis fan

Check the setting for that CHA_FAN Header in the UEFI - if it is set to 100%, then no matter what you want the software to do it will not over rule the BIOS setting. See page 2-36 here http://images10.newegg.com/UploadFilesForNewegg/itemintelligence/ASUS/E7828_Z87_A1405404469904.pdf and check your Q-Fan settings for each of the 3 SYS/CHA headers.

Try switching the fans on the pins first - see if its the MOBO or if it's just the FAN. Not really worth RMAing the board if it's just a shoddy $5 Fan.

Also, try changing the BIOS setting for that header from Auto to Q-Fan, Manual or PWM and see if you can control it. Are they 3 Pin or 4 Pin Fans - if 4 pin, you should be able to manage them through PWM - if 3 pin, Q-Fan

Which Corsair Fans are they? AF140mm?

Have you tried using a Y splitter and running 2 fans of the same Header that you know is working?

DO you need to run 4 x case fans?

So all your fans do the same thing on the mobo CHA_FAN3 - that is, they run constantly at full speed. That is exactly what will happen if you plug a 3-pin fan into a 4-pin mobo port. So, are all your fans 3-pin? Is the CHA_FAN3 port for a 4-pin fan? Or, is the BIOS Setup option for that mobo port set to behave as a 4-pin fan port (i.e., use PWM control)? If there is an option, change it to 3-pin mode (i.e., use Voltage control).

No, that Mobo allows 3 pin fans to be controlled by Q-Fan via Voltage and RPM feedback - what he is saying, he can control 2 of the 3 SYS_FAN Headers - the 3rd one is stuck on 100% and it won't throttle no matter the BIOS Setting. If you follow the link I supplied in the previous post to the MOBO Manual, you will see it supports Q-Fan on the 3 Chassis headers. - http://images10.newegg.com/UploadFilesForNewegg/itemintelligence/ASUS/E7828_Z87_A1405404469904.pdf Page 2-36

I am having the same issued but with my Corsair 460x RGB case that includes 3 Corsair SP 120 RGB fans and Asrock Z170 Pro4S mobo. This board has 2x 4-pin header (CHA_FAN 1 and 2), 1x 3-pin header (CHA_FAN 3) and 1x 4-pin CPU header. When I change the fan settings either in the BIOS or thru Asrocks software, only the CPU and CHA_FAN 1 will adjust, the other two fans will run full speed. Which is confusing to me because CHA_FAN 1 and 2 are EXACTLY the same yet I cannot control CHA_FAN 2. I should note that these fans are all 3-pin but still I can control CHA_FAN 1 which is a 4-pin header but not CHA_FAN 2.

I would NOT expect that mobo to be able to control the speed of any 3-pin fan from its CHA_FAN1 or 2 headers. That's because the pinout labels on manual p. 22 indicate that they both operate in PWM Mode and the Monitor portion of the manual says nothing about changing that mode. So, if you really have a 3-pin fan on CHA_FAN1, I am puzzled that you can change its speed. Now, CHA_FAN3 is another matter entirely. Its pinout labels say it does no control at all, and so its fan will always run full speed, so that is no mystery.

Check that you do have a 3-pin fan on CHA_FAN1, and that its speed does change.

The other item to check (see manual p.72-3) for each of those two CHA_FAN headers is its "Temp Source". For both it should be set to the sensor built into the mobo, and NOT the sensor inside the CPU chip.

We still have the issue of how to power and control three case ventilation fans from your available CHA_FAN headers, since one of those headers cannot control anything. But first, I need to know for sure whether the CHA_FAN1 header really is changing the speed of a 3-pin fan.

Thanks for the response. I just received an email response from ASRock, "Only CPU_FAN1 and CHA_FAN1 can auto detected with 3 pins connector. If case fan connector is 3 pins that may not be worked on CHA FAN2, and CHA FAN 3 is not adjustable.". I guess that explains why I can only adjust the speeds of CHA_FAN 1 and CPA_FAN. So now it's just a matter of figuring out how I can make this work since I only have 1 header will allow me to adjust the speed and 3 case fans. I just received another SP 120 RGB I ordered a few days ago to use as an exhaust fan in CHA_FAN 3. What are my options given the situation? What about a fan hub? I already have the hub and controlled that is included with the case but that is solely for lighting not speeds.

There actually is a simple solution. The key is to know exactly how the headers work, and how that affects control of 3-pin fans.

Major clue from what ASRock Tech Support told you: both the CPU_FAN and the CHA_FAN1 headers will do automatic detection of the fan type connected, and adjust themselves accordingly. The manual does not tell you this. So that CHA_FAN1 header IS changing itself to operate in Voltage Control Mode, which is what any 3-pin fan needs. However, the CHA_FAN2 header does not do this, it only operates in PWM Mode. And CHA_FAN3 has no control ability at all.

Next we deal with multiple fans on one header. Generally, any mobo fan header can supply up to 1.0 amps for all its fans in total. Now the SP120 High Performance fans's specs say they consume 0.18 amps each, so hypothetically you could afford to connect up to 5 fans (0.90 amps total) to one mobo header. You say you have 3 - or is that 4 with the new one on the way? Do-able.

Next, how to do that? You will be working with the CHA_FAN1 header that uses Voltage Control Mode, and connecting to it only 3-pin fans. So a fan HUB that only operates for 4-pin fan systems is NOT how to do it. You need a SPLITTER. This is a device that looks like a group of wires and connectors. It has one arm with a female (with holes) connector on it that plugs into a mobo fan header. Then it has 2 or 3 output arms each having pins, for plugging your fans into. This device merely connects the fans together in parallel to share the power from the header. It also is rigged (by missing Pin #3 on one or two of it outputs) to send back to the header the speed signal on only ONE of its fans. (To distinguish, a Hub may look like this, too, but it has one EXTRA arm that ends in a connector to plug into a power output from your PSU, and that's where it gets fan power. But a Hub MUST have a PWM signal, and can only control 4-pin fans.) You should be aware that it does not matter whether the Splitter is for 3- or 4-pin fans, because either type will fit your system and connect your 3-pin fans properly.

Here's an example of a Splitter for 3-pin fans with two outputs.

http://www.newegg.com/Product/Product.aspx?Item=N82E16812423168&cm_re=coboc_fan_splitter-_-12-423-168-_-Product

If you buy three of these and "stack" them by plugging two into the outputs of the third one, that will convert one mobo header into four fan outputs, and you could hook four fans up to the CHA_FAN1 header.

Here is a Splitter for 4-pin systems with three outputs

http://www.newegg.com/Product/Product.aspx?Item=N82E16812423162&cm_re=coboc_fan_splitter-_-12-423-162-_-Product

With one of these you could connect three fans to one header.

When you do this, the CHA_FAN1 header will detect that it is dealing with 3-pin fans and start using Voltage Control Mode (as it already has demonstrated it can do), and ALL your case fans can be automatically controlled by that mobo header.

Thanks for the reply. I was planning on using the 4th fan I just received as an exhaust fan plugged into CHA_FAN 3 so it would just be the 3 case fans going into CHA_FAN 1. I am going to buy that splitter with theee outputs now.

Sounds good. Let us know how it works.

Just an FYI incase anyone else comes across this problem with this motherboard. the fan splitter plugged into CHA_FAN1 solves the problem.