Fan Problem in Asus Z97 Deluxe

[jvillaveces]

I recently installed a custom watercooling loop in my system and put in an Aquaero 6 Pro. All my former case fans became radiator fans, and they are controlled by the Aquaero. I still have one case fan in the rear position, hooked to the motherboard. My system specs:

- Case: Corsair 760T
- Motherboard: Asus Z97-Deluxe, BIOS 2205
- CPU: i7 4790K @4600 MHz
- RAM: 16 GB Corsair Dominator PLatinum 2133 MHz
- GPU: 2x GEVGA GTX980 SC
- Storage: Hyper X Predator m.2 240 GB, 2x Intel 730 240 MB SSD, 2x Intel 730 480 MB SSD
- Fan Control: Aquaero 6 Pro, Aquasuite

Because there is no fan in the CPU header, I set the BIOS to ignore it so the system would start.
My problem is that the rear fan will not be detected by the mobo. It's a led fan (Corsair AF140 led), and it's lit, so I know it's getting power, but it won't spin, and the BIOS reports no fan in that position. At first I thought I had a defective fan so I put in a new one, but that one doesn't work either.
When the second fan failed to operate correctly, I tried plugging it to different headers around the motherboard to see if it worked. It turns out that it will spin normally in the CPU_OPT header, and in CHA-FAN3 and CHA_FAN4, but not in CHA_FAN1 or CHA_FAN2.
I have tried Manual Fan Tuning, setting it to both PWM and DC control with no results. Interestingly, if I set it up as DC, the "Fan Off" option becomes avilable, and if selected, the LEDs go off.
Of course it's possible that two fan headers on my motherboard just died for no particular reason, but it's more likely that there is something wrong with the way I have configured the BIOS. Please help!

 

[i7Baby]

Is the fan PWM or voltage control?

Are the chassis fan headers pwm or voltage control?

 

[jvillaveces]

Tricky question. Corsair calls it PWM but it's a 3-pin fan.
The headers are all 4-pin, and in BIOS you can select all headers as either DC or PWM.
Before putting in the custom loop, I was running all my fans from the motherboard headers without a problem. My problem only started after I set the CPU header to "ignore".

 

[alexoiu]

What happens if enabling the CPU_Fan in BIOS and connecting the fan to the CPU header?
If working, I suggest leaving it like that.

 

[i7Baby]

Tricky question. Corsair calls it PWM but it's a 3-pin fan.
The headers are all 4-pin, and in BIOS you can select all headers as either DC or PWM.
Before putting in the custom loop, I was running all my fans from the motherboard headers without a problem. My problem only started after I set the CPU header to "ignore".

What exact model is the rear fan. 3 pin means not pwm.

Not many people would try this. I suggest you contact Asus. I have a feeling that CPU header off might mean no rpm feedback. And this could be from all the headers. Maybe screwy programming.

Also try a bios update.

 

[jvillaveces]

The fan is AF140 Quiet Edition.
I share the suspicion that turning off the cpu fan in BIOS has unintended consequences on the other fan headers. What puzzles me is that two of them (3 and 4) still operate normally.
A simple workaround for my problem is to plug in the fan in into one of the headers that work (I have), but it's not optimal from the point of view of cable management. Also, more importantly, I don't like not knowing what is going on. There are several issues with this motherboard where I've found workarounds, without ever solving or even fully understanding the underlying problem. I hate that!

 

[i7Baby]

I suggest you contact Asus.

 

[jvillaveces]

Problem solved. I set all the headers to pwm, rebooted, set them all to DC, rebooted again, and everything worked.

 

[i7Baby]

Nice one.