Question Rear fan at max speed after installing AIO

[nikkitheknife]

I upgraded my build to an AIO liquid cooling kit. Now my rear fan is running at max speed. The AIO seems to be working fine, other fans are working fine, it's just the rear fan. Went into BIOS and tried to change it there, but it isn't responding and just continues running at full speed. It was not doing this before installing the AIO. Not sure what to do next.

 

[Lutfij]

Welcome to the forums, newcomer!

We're going to need a little more info. When posting a thread of troubleshooting nature, it's customary to include your full system's specs. Please list the specs to your build like so:
CPU:
CPU cooler:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
include the age of the PSU apart from it's make and model. BIOS version for your motherboard at this moment of time.

I upgraded my build to an AIO liquid cooling kit.
What were you working with prior and what did you upgrade to? A link would help us two fold. Which header on your motherboard is the rear fan hooked up to?

 

[alceryes]

What do you have the AIO fan plugged into? Motherboard fan header or standard 4-pin molex? If it's the motherboard header which one?

 

[Paperdoc]

Rear fan details would help. ONE reason for this can be if the fan is an older THREE-pin fan. That is, its cable has THREE wires and ends in a connector with THREE holes. That CAN be plugged into a mobo fan header with 3 OR 4 pins. IF you plug an older 3-pin fan into a 4-pin header, MOST headers offer an option in BIOS Setup for the MODE of the header. Mode is the type of signals sent to the fan to control speed. A 3-pin fan MUST be fed by a header using the older Voltage Control Mode (aka DC Mode). A 4-pin fan should have the header set to PWM Mode.

Also make sure the header PROFILE is not set to Turbo or Manual or something like that. It should be set to Standard or Normal.

 

[nikkitheknife]

Welcome to the forums, newcomer!

We're going to need a little more info. When posting a thread of troubleshooting nature, it's customary to include your full system's specs. Please list the specs to your build like so:
CPU:
CPU cooler:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:
include the age of the PSU apart from it's make and model. BIOS version for your motherboard at this moment of time.

I upgraded my build to an AIO liquid cooling kit.
What were you working with prior and what did you upgrade to? A link would help us two fold. Which header on your motherboard is the rear fan hooked up to?

CPU: AMD Ryzen 7 5800x 8-core 3.8GHz AM4
CPU cooler: Lian Li GA II Trinity 360 AIO kit
Motherboard: MSI Mag B550 Gaming Plus
Ram: G. Skill Trident Z Royal 32 GB (2 x 16GB) DDR4-3600
SSD/HDD: Samsung 860 EVO 500GB 2.5" SATA III
GPU: ASRock Radeon RX 7600 Steel Legend 8GB
PSU: EVGA SuperNova 850 GT
Chassis: Montech King 95 Dual-Chamber ATX Mid-Tower
OS: Windows 11 Home

PSU is about 2 years old.
BIOS Version: E7C56AMS.1A0

Previously had an AMD Ryzen 5 5600 6-core CPU w/an AMD Wraith Prism RGB 4-pin CPU cooler. Link to the new cooling kit: https://www.microcenter.com/product...360mm-all-in-one-liquid-cpu-cooling-kit-white

Rear fan is currently connected to mobo SYS_FAN1. We also tried moving it to SYS_FAN2 (which currently has a front fan connected that works fine - the issue seems to follow the fan regardless of which port we swap it to) and it still continued to run at max speed.

The rear fan is a Corsair AF120 Elite. It did not start running at max speed until I upgraded the CPU and put the AIO kit on. The top/rad AIO fans are running fine. I also have two Corsair AF140 Elite front fans that are running fine.

I downloaded the Lian Li L-Connect software as one of the AIO fans was not lighting up at first install due to it needing to be "turned on" in the software first. Weird, but okay. So now all the AIO fans are running fine and lighting fine. Just the rear fan decided to max out. Light is still fine. Went into BIOS to try adjusting the rear fan speed in the settings and the fan did not respond. It continued running full speed no matter what speed it was changed to in BIOS. Fan cable seems to be okay - no notable damage.

 

[nikkitheknife]

Rear fan details would help. ONE reason for this can be if the fan is an older THREE-pin fan. That is, its cable has THREE wires and ends in a connector with THREE holes. That CAN be plugged into a mobo fan header with 3 OR 4 pins. IF you plug an older 3-pin fan into a 4-pin header, MOST headers offer an option in BIOS Setup for the MODE of the header. Mode is the type of signals sent to the fan to control speed. A 3-pin fan MUST be fed by a header using the older Voltage Control Mode (aka DC Mode). A 4-pin fan should have the header set to PWM Mode.

Also make sure the header PROFILE is not set to Turbo or Manual or something like that. It should be set to Standard or Normal.

They're all 4-pins and we did go into BIOS already and check the settings. Rotating fan ports did not solve the issue and when attempting to adjust the rear fan speed via BIOS, it did not respond and change speed, it just continues to max out.

 

[Paperdoc]

That rear fan is behaving as if it were an older 3-pin fan, but it is NOT. So it has a flaw. Two possibilities.
1. The MORE likely is that the wire for Pin #4 that carries the PWM signal from header to fan has a break or a bad connection, so that the fan receives NO PWN signal to use. So it never changes its speed and always runs full speed. Look closely along that wire, and use an Ohmmeter to measure its resistance from the connector end to the fan body. Pay special attention to the little metal parts inside the hole for Pin #4 of the connector. Unfortunately, it also is possible that the break / bad connection is inside the motor case and cannot be accessed.

2. LESS likely: the small chip inside the motor that uses the PWM signal for speed control has failed and is not doing its job normally. Produces this same result, but cannot be repaired.

 

[nikkitheknife]

What do you have the AIO fan plugged into? Motherboard fan header or standard 4-pin molex? If it's the motherboard header which one?

That rear fan is behaving as if it were an older 3-pin fan, but it is NOT. So it has a flaw. Two possibilities.
1. The MORE likely is that the wire for Pin #4 that carries the PWM signal from header to fan has a break or a bad connection, so that the fan receives NO PWN signal to use. So it never changes its speed and always runs full speed. Look closely along that wire, and use an Ohmmeter to measure its resistance from the connector end to the fan body. Pay special attention to the little metal parts inside the hole for Pin #4 of the connector. Unfortunately, it also is possible that the break / bad connection is inside the motor case and cannot be accessed.

2. LESS likely: the small chip inside the motor that uses the PWM signal for speed control has failed and is not doing its job normally. Produces this same result, but cannot be repaired.

Thank you! This is exactly what my husband said HAHAHA. I'm going to have Corsair send me a new one.