Question The Radiator Fans have different RPM

[rizangg]

Hello everyone.

Just recently, I bought Cooler Master Masterliquid ML120L RGB for my i5 9600K CPU. The cooler package contains only one radiator fan (Masterfan MF120AB), so later I bought another fan (Masterfan MF120AB Pro RGB) for push-pull radiator fan configuration (rear exhaust). Both fans are RGB but I didn't realize that they are slightly different until I receive the second fan. Apparently, Masterfan MF120AB Pro RGB has a switch on the rear to manually set the RGB lights.

This is my CPU cooler configuration:

• The pump power line (3 pins) connected to CPU FAN Header (4 pins)
• Both fans power line (4 pins) connected to two different SYS FAN Header (4 pins)
• The pump RGB line (4 pins) and the fans RGB line (4 pins) connected to line splitter (joiner?) and connected to RGB Header (4 pins)

The idle CPU temperature is at 32-34 degree Celsius. I tested bench my CPU using Cinebench R15 and the temperature goes up to 57 degree Celsius, I think it's a pretty good temperature. But here is the problem (or not?), the hardware monitor (from MSI Dragon Center) shows that the two radiator fans have different RPM, 1200~ RPM and 700~ RPM. Is it normal? Is it because both fans are not the same type? Is it a problem? My motherboard is MSI Z390A Pro and has a PUMP header (4 pins).

Thanks.

 

[Lutfij]

You might want to swap the fans connections with each other and see if the speeds change for the one that is now being shown as the slower among the two. Ideally you have a water pump header so I'd ask you to connect the pump to that and have one of the two fans on the CPU Fan header. Later grab a PWM fan splitter and have both fans off said splitter. To add, can you please pass on a link to the fan you purchased?

 

[rizangg]

Thank you for your response.

I changed the configuration:

• The pump power line connected to PUMP Header (previously CPU FAN header), the speed is roughly the same as before (2000~ RPM).
• Included fan power line connected to CPU FAN Header (previously SYS FAN 5 header), the speed went up from 1200~ RPM to 2000~ RPM and getting louder. I think it's at 100% speed.
• Additional fan power line connected to SYS FAN 5 header (previously SYS FAN 4 header), the speed is roughly the same as before (700~ RPM).

Is it normal for the speed of radiator fan goes up when connected to a different type of header? I am a little worried.

This is the link:
Liquid Cooler: http://www.coolermaster.com/cooling/cpu-liquid-cooler/masterliquid-ml120l-rgb/
Additional Fan: http://www.coolermaster.com/cooling/case-fan/masterfan-pro-120-ab/

Upon reading the specifications from the link above, I realized I choose the wrong additional fan. They are not slightly different.

 

[Karadjgne]

Ideally you'll have both fans from the same header via a splitter. That way both are run simultaneously at the same duty cycle as per the same temp sensor (cpu). Using a system header as well just confuses the issue since one fan will be operating via case or motherboard temps and the other by cpu temps.

Generally, with the design properties of newer fans, push/pull doesn't get but 2-3°C bonus to cpu temps, under duress. At idle you'll not see anything, at small loads you'd have to know the exact temp to see any difference. It usually ends up being more of a hassle, especially wiring with RGB.

 

[Paperdoc]

The names you cite don't exactly match what Cooler Master uses on their website now, but I think I've got these decoded. The cooling system came with a MasterFan MF120R RGB fan that will run in the range 600 to 2000 RPM, generating max airflow of 59 CFM against no back pressure, and able to work against a max back pressure of 2.14 mm water. Then you added a MasterFan Pro 120 Air Balance RGB fan, which will run in the range 650 to 1300 RPM, generating max airflow of 43 CFM against no back pressure, and able to work against a max back pressure of 0.96 mm water. These have rather different specs, so when fed exactly the same signals they each WILL operate at different speeds, and would generate different air flows IF they were independent. But in fact you have them mounted in a push / pull configuration on a radiator, and the old rule applies: what goes in must come out. So the actual air flows through those two fans is exactly the same, irrespective of what different speeds they actually are turning. So do not worry about whether their speeds match.

However, the two fans are doing exactly the same job, and need to be co-ordinated. As Karadjgne says, their motors really should be receiving the same control signals from the same mobo CPU_FAN header, so they should both be connected to that header using a simple two-output SPLITTER like this.

https://www.newegg.com/Product/Prod..._re=coboc_fan_splitter-_-12-423-160-_-Product

This is completely separate from the RGB lighting cables from the two fans, which also can be fed identical signals (using a different RGB Splitter) from a mobo plain RGB header (4-pin 12 V system) on your mobo if it has one.

 

[Karadjgne]

Well system headers have different sensors, spaced around the motherboard. If that particular header is responding to case temps, it might see 40°C ish, so barely ever get past idle. If it's tied into a sensor next to the pcie bridge or VRM's or Sata controller, it could see temps in access of 90°C ish. Fan would never see less than max. Ideally you want fans responding to the cpu, since it's a cpu cooler 😊

 

[rizangg]

The names you cite don't exactly match what Cooler Master uses on their website now, but I think I've got these decoded. The cooling system came with a MasterFan MF120R RGB fan that will run in the range 600 to 2000 RPM, generating max airflow of 59 CFM against no back pressure, and able to work against a max back pressure of 2.14 mm water. Then you added a MasterFan Pro 120 Air Balance RGB fan, which will run in the range 650 to 1300 RPM, generating max airflow of 43 CFM against no back pressure, and able to work against a max back pressure of 0.96 mm water. These have rather different specs, so when fed exactly the same signals they each WILL operate at different speeds, and would generate different air flows IF they were independent. But in fact you have them mounted in a push / pull configuration on a radiator, and the old rule applies: what goes in must come out. So the actual air flows through those two fans is exactly the same, irrespective of what different speeds they actually are turning. So do not worry about whether their speeds match.

However, the two fans are doing exactly the same job, and need to be co-ordinated. As Karadjgne says, their motors really should be receiving the same control signals from the same mobo CPU_FAN header, so they should both be connected to that header using a simple two-output SPLITTER like this.

https://www.newegg.com/Product/Product.aspx?Item=N82E16812423160&Description=coboc fan splitter&cm_re=coboc_fan_splitter--12-423-160--Product

This is completely separate from the RGB lighting cables from the two fans, which also can be fed identical signals (using a different RGB Splitter) from a mobo plain RGB header (4-pin 12 V system) on your mobo if it has one.

Thank you for your response. Yes, I finally found the problem. The fans basically have different speed. When I was looking for an additional fan, I didn't check the included fan specifications from the website. I unknowingly bought MasterFan Pro 120AB RGB because of the label on the rear included fan says MasterFan 120AB (not MasterFan MF120R RGB) as shown below.

Spoiler: the fans

They look the same, right?

Well system headers have different sensors, spaced around the motherboard. If that particular header is responding to case temps, it might see 40°C ish, so barely ever get past idle. If it's tied into a sensor next to the pcie bridge or VRM's or Sata controller, it could see temps in access of 90°C ish. Fan would never see less than max. Ideally you want fans responding to the cpu, since it's a cpu cooler 😊

Thank you for your responses. I am confused. The fan is connected to CPU FAN header, but why it doesn't respond to CPU temperature but instead running at full speed even though the CPU only at 32-36°C? Is the fan has a standalone temperature reading?

 

[Karadjgne]

Check your bios. You previously had the pump set there, if bios has set a fixed max, it'll stay that way. You may need to change the cpu setting back to its normal settings for a fan.

 

[CountMike]

For best cooling results with that cooler, make sure pump runs full speed all the time. Original radiator fan should be in push position and any added fan as pull. Ideally they should run at same speed and being controlled from same header, CPU_Fan and Aux CPUfan if MB has one.

 

[rizangg]

Check your bios. You previously had the pump set there, if bios has set a fixed max, it'll stay that way. You may need to change the cpu setting back to its normal settings for a fan.

I checked the BIOS and it turned out the smart fan setting is disabled when OC Genie is on. Thank you for your answer. 🙏🏻🙏🏻🙏🏻

For best cooling results with that cooler, make sure pump runs full speed all the time. Original radiator fan should be in push position and any added fan as pull. Ideally they should run at same speed and being controlled from same header, CPU_Fan and Aux CPUfan if MB has one.

Yeah, the pump is always running at full speed. I tried overcloking my CPU at 5GHz 1.35V, one of the cores temperature reach 79 degree Celsius. Is it safe temperature?

 

[Karadjgne]

Doing what? If 79 is under stress testing, then that's OK, you'll be gaming at mid 50's-60ish. If 79 is idle, that's not ok. Either way, if manually OC, then reset the bios and make doubly sure OC Genie is fully disabled because many times it'll change settings when it's run and forget to change them back when it's stopped.

 

[rizangg]

Doing what? If 79 is under stress testing, then that's OK, you'll be gaming at mid 50's-60ish. If 79 is idle, that's not ok. Either way, if manually OC, then reset the bios and make doubly sure OC Genie is fully disabled because many times it'll change settings when it's run and forget to change them back when it's stopped.

Yes, it's under a stress test. The idle temperature was around 32-35 degree Celsius, but it could spike up to 50 degree Celsius for a moment. Is it safe for fans running at full speed all the time?

 

[Karadjgne]

Sure. It's actually less stress on the motor as the fan blades are providing momentum.

It's just annoying to listen to.

Spikes at idle are perfectly normal. Cpu temps get reported 2x a second. The heatsink takes a second to absorb the heat and dissipate it. So when windows does something in the background, it creates a momentary load, spikes the temps to @ 45-50°C then settles down again.

I can't see anything wrong temp wise, you are good. Fan speeds and associated temps are up to you, most fan curves default to max speed anyways at @ 70°C. But the cpu honestly doesn't care. To a cpu, 50°C is exactly the same as 80°C, the cpu has only 2 different criteria. Operating range and Throttle range. As long as you are in operating range, you are good. That's generally under @ 70°C ish.

 

[rizangg]

Sure. It's actually less stress on the motor as the fan blades are providing momentum.

It's just annoying to listen to.

Spikes at idle are perfectly normal. Cpu temps get reported 2x a second. The heatsink takes a second to absorb the heat and dissipate it. So when windows does something in the background, it creates a momentary load, spikes the temps to @ 45-50°C then settles down again.

I can't see anything wrong temp wise, you are good. Fan speeds and associated temps are up to you, most fan curves default to max speed anyways at @ 70°C. But the cpu honestly doesn't care. To a cpu, 50°C is exactly the same as 80°C, the cpu has only 2 different criteria. Operating range and Throttle range. As long as you are in operating range, you are good. That's generally under @ 70°C ish.

Thank you so much for your answer