Troubleshooting AIO CPU Fan Speed Cycling Issues

[jroscoe1980]

Hi All,

 

First time here but been watching LTT for the past year.  I've been a console gamer for the majority of my life but decided to finally dive into the PC world.  Dipping my toes into it with a pre-built from Redux.

 

I just got my build delivered yesterday and I am having an issue with the CPU fan monitor showing the fan speed cycling between 0 and what I assume is the fan speed but the ranges it displays are all over the place.  Bios monitor shows it cycle between "Disconnected" and the same erratic fan speeds at the CPU header.

 

Motherboard: MSI B460M-A Pro

CPU Cooler: Cooler Master ML240L (Dual Fans)

 

All bios, firmware, and drivers are up to date.  I am trying to see if I can trace the issue to either a bad part or an improper install from Redux.

 

Based on what I can see, the cpu cooler fans are running a PWM Splitter to a separate controller that is running all of the case fans and rgb.  The splitter runs to the "PWM" connection on that board.  That controller board then runs to the CPU fan header on the motherboard.

 

Assuming that this is the proper way to run those connections, I'm also looking at the possibility of the wrong pins being tapped at the cpu header.  The header is a 4 pin connection but only 2 wires are being run to the connector.  Based on the info I have found, the cpu header pin layout when in PWM mode is as follows:

 

1 - Ground

2 - +12V

3 - Sense

4 - Speed Control Signal

 

The cable running from the controller board to the cpu header is running to pin #s 3 & 4.  So it's getting "Sense" and "Speed Control Signal" only.

 

Just looking for some feedback from people more experienced and knowledgeable than I am at this point.  Am I looking at a simple re-wire for the proper pins, a bad controller, or a bad cpu fan header on the MB?

 

Thanks to anyone that takes the time to read this and reply with any help or suggestions.

[Juular]

Does the pump block sound right ? I.e steady whining, not intermittent as it would've been if the impeller is struggling to rotate. What's your CPU, it's temperature and coolant temperature after ~15 min of OCCT / Linpack stress test ?

[jroscoe1980]

37 minutes ago, Juular said:

Does the pump block sound right ? I.e steady whining, not intermittent as it would've been if the impeller is struggling to rotate. What's your CPU, it's temperature and coolant temperature after ~15 min of OCCT / Linpack stress test ?

Honestly, it's hard to tell.  The system remains pretty quiet unless the gpu fans ramp up during gaming.  I believe the impeller is fine.  I did get the typical few mins of bubbling/gurgling at my first start up, which is now gone.  No whining or odd noises at all from the water cooling system.

 

The CPU is an i5 10400, so no OC.  I didn't run any heavy stress testing.  I did run Cinebench while using the MSI monitoring software.  Clocks remained around the 3800MHz range.  CPU Fan 1 was showing readings from 0 to sudden jumps between 600-1000rpm randomly.  System Fan 1 readings were not cycling to 0 and stayed steady in the 2300-2400rpm range.

 

CPU core temps had a brief spike to 51C but tended to hold steady at 49C for most of the testing.  At idle, cpu core temps are at 26C.

 

As a sanity check, I took off the sides of the case to confirm that the cooler fans were actually spinning, and they are.  I did not notice any hitching, noises, or sudden observable changes to fan speed.  They both looked to just be both running at the same constant speed regardless of what the readings were showing.  No spins down to 0 or obvious slow downs caused by a temporary power loss or disconnection.

 

I'm a bit at a loss.  The system itself seems to be operating fine, but something is causing the cpu fan readings to drop out every few seconds and the speeds it does read don't seem to be accurate.

 

I think the case fan/rgb controller board is running both the cpu and case fans at the same constant speed.  This would mean that the motherboard is not in control of the cpu fan speed based on load, but with the connection between the controller and the motherboard's cpu fan header, it must be throwing some funky readings.  If I disconnect the fan/rgb controller board from the cpu fan header on the motherboard, then the cpu cooler fans still spin.  I just have to disable the cpu fan error in bios to avoid the cpu fan errors at startup and then never pay attention to cpu fan speeds when monitoring performance.

 

Given that my cpu isn't anything crazy or overclocked, I assume that unless temps are an issue, it's not a huge deal to just let the fans run at the same speeds without any control from the cpu/motherboard based on load, but I'd still prefer to have the cpu cooler fans running properly in support of the cpu temps if that is possible.

 

I'm thinking that I'd need to take the fan/rgb controller out of the loop and just run the PWM splitter to the cpu header on the motherboard per the normal installation instructions I'm finding for the cooler.

[jroscoe1980]

SOLVED

 

Disconnect the cpu cooler pwm splitter from the case fan/rgb pcb board and run it directly to the cpu fan header on the motherboard.

 

This fixed all of my issues.  CPU Fan readings are now constant with no erratic drops.  Case fans now run independently from the cpu and I can increase/decrease the case fan speeds along with rgb settings using the remote Redux included with the system.

 

I have no idea why Redux chose to run the cpu cooler fans this way.  Maybe it was a fluke on my particular build, but if they are doing this as standard then they need to change that and just leave the cpu cooler fans running directly to the motherboard and keep the case fans/rgb running independently off the separate pcb.

 

If anyone has a build from Redux with a similar issue, and you happen to stumble onto this, then check how your cooler fans are routed.  The 2 fans should run to a Y-shaped cable that joins the 2 fans into a single connection.  If that connection is running to a separate board (not the motherboard) where you also see connections for the 3 front case fans and the rgb, then remove it from there, and connect it to the cpu fan 1 spot on the motherboard.  If there is something that is already plugged into the cpu fan header spot on the motherboard, then simply remove it.  It doesn't need to go anywhere else.

 

It will allow the system to control the cpu cooler fans based on cpu temps rather than have the cooler run at the same constant speed at all times regardless of cpu loads.