Question AIO pump changes RPM while connected to CPU_OPT header ?

[AndyVG]

Hi,

I truly do not know what to try anymore. I have heard others with the same problem as myself with deepcool LT720 and LT520 coolers. My PC is brand new and so is my deepcool LT520 AIO. It is connected to the CPU_OPT header on my ASUS PRIME B550M-A WIFI II mother board and the radiator fans connected to the CPU_FAN header. the pump runs at the normal 3100 +/- 10% RPM at most times (deepcool support says it should be running at that speed at all times) but after some random amount of time eventually, the RPM will drop to ~2400 RPM making a loud humming noise. Why is the AIO pump speed changing when connected to CPU_OPT? I thought the pump being connected to CPU_OPT will mean it runs at 100% at all times? The pump is 3 pin and rad fans are 4 pin. Motherboard manual does not say anything regarding AIO pumps.

I have tried swapping the fan connection and and pump connection and set the pump connected to CPU_FAN to run at 100% in bios but changing the CPU_FAN curve with this setup only changes the radiator fan RPM! Could there be something in BIOS I could change to ensure CPU_OPT is always running at 100%? I didn't see anything in the BIOS when I looked. I cannot figure out how to change the CPU_OPT speed in bios or through any other software so far. I've heard that the CPU_OPT may follow the CPU temps and you are generally unable to adjust the fan profile for CPU_OPT. After shutting off and turning on the PC again, the pump runs at ~3100 RPM until it decides to eventually reduce its speed again. Am I SOL and need to buy a different cooler brand?

Also this is my first time building a PC so I might be missing something.

Thanks for any insight.

 

[Lutfij]

Welcome to the forums, newcomer!

The CPU_OPT fan header is a secondary fan header that base's it's behavior off of the CPU_FAN header. you could go into BIOS and set the RPM for that header to max/disabled.

What BIOS version are you on for your motherboard?

 

[AndyVG]

Welcome to the forums, newcomer!

The CPU_OPT fan header is a secondary fan header that base's it's behavior off of the CPU_FAN header. you could go into BIOS and set the RPM for that header to max/disabled.

What BIOS version are you on for your motherboard?

Hello, I am unable to adjust the RPM to the CPU_OPT header in BIOS. I can only change CPU_FAN.

My bios version is 3002.

 

[CountMike]

Hello, I am unable to adjust the RPM to the CPU_OPT header in BIOS. I can only change CPU_FAN.

My bios version is 3002.

In that case both headers have same input and output. Two different motors (Pump and fans) can confuse speed regulation. Try some other fan header, Unfortunately, MB doesn't have AIO_PUMP header nut there are 2 chassis fan headers to plug pump in.

 

[Dragos Manea]

Yes, use a chassis fan and set that particular header to 100%.

 

[Paperdoc]

There are other threads on this forum reporting such odd speed behaviour in these AIO systems. I don't know why this happens, or whether it affects your system, However, I will detail a "trick" you should use to see if it helps.

This all depends on the difference in design of 3- and 4-pin fans, and how they act when "mis-matched". Because of the designs, if you plug a 3-pin fan into a mobo header using the newer 4-pin MODE of signals, that fan will always run full speed. Now it happens that is exactly what we WANT for the PUMP in an AIO system. AND the PUMP unit is wired exactly like an older 3-pin fan.

SO, connect the PUMP unit to the CPU_FAN header, and the RAD FANS to the CPU_OPT header. As you say, you are allowed to adjust only the CPU_FAN header, and the CPU_OPT header merely mimics that first one. So set the CPU_FAN header to the normal Standard Profile at the bottom but make SURE at upper right you set it to use the newer PWM Mode. This WILL adjust the speeds of the RAD FANS that are of the 4-pin design, but the PUMP speed cannot be adjusted this way so it will always run full speed. Having that pump on the CPU_FAN header ensures that a second important function is working. That CPU_FAN header (and sometimes but not for sure, the CPU_OPT header) monitors the speed signal sent back to it from its "fan" (in your case, the PUMP plugged in there) for NO signal indicating failure. IF that ever happens it will pop a warning onto your screen and, in a short time, shut your system down completely without even waiting for the temp sensor inside the CPU chip to report high temps. This is to protect the valuable CPU chip from damage by overheating when it gets NO cooling. In an AIO system, the critical item to monitor for failure is the PUMP.

People in other threads concerning this AIO system have reported that even when the pump is fed with the constant full 12 VDC power supply it requires, it does change its speed by itself. I do NOT know how or why, nor whether that would happen with your system. But doing as I outline above will guarantee the pump gets a constant full power signal to run full speed.

 

[AndyVG]

There are other threads on this forum reporting such odd speed behaviour in these AIO systems. I don't know why this happens, or whether it affects your system, However, I will detail a "trick" you should use to see if it helps.

This all depends on the difference in design of 3- and 4-pin fans, and how they act when "mis-matched". Because of the designs, if you plug a 3-pin fan into a mobo header using the newer 4-pin MODE of signals, that fan will always run full speed. Now it happens that is exactly what we WANT for the PUMP in an AIO system. AND the PUMP unit is wired exactly like an older 3-pin fan.

SO, connect the PUMP unit to the CPU_FAN header, and the RAD FANS to the CPU_OPT header. As you say, you are allowed to adjust only the CPU_FAN header, and the CPU_OPT header merely mimics that first one. So set the CPU_FAN header to the normal Standard Profile at the bottom but make SURE at upper right you set it to use the newer PWM Mode. This WILL adjust the speeds of the RAD FANS that are of the 4-pin design, but the PUMP speed cannot be adjusted this way so it will always run full speed. Having that pump on the CPU_FAN header ensures that a second important function is working. That CPU_FAN header (and sometimes but not for sure, the CPU_OPT header) monitors the speed signal sent back to it from its "fan" (in your case, the PUMP plugged in there) for NO signal indicating failure. IF that ever happens it will pop a warning onto your screen and, in a short time, shut your system down completely without even waiting for the temp sensor inside the CPU chip to report high temps. This is to protect the valuable CPU chip from damage by overheating when it gets NO cooling. In an AIO system, the critical item to monitor for failure is the PUMP.

People in other threads concerning this AIO system have reported that even when the pump is fed with the constant full 12 VDC power supply it requires, it does change its speed by itself. I do NOT know how or why, nor whether that would happen with your system. But doing as I outline above will guarantee the pump gets a constant full power signal to run full speed.

Hello,

I have tried to apply your suggestion, and have connected the pump to CPU_FAN and the radiator fans to CPU_OPT. After going into BIOS, the CPU_FAN was set to standard profile, however I can not see any option to change to PWM mode on the top right for CPU_FAN. I can see this option for my Chassis fans (CHA1_|FAN & CHA2_FAN) but not for CPU_FAN. Please see attached photos.

When rebooting the PC with pump connected to CPU_FAN, it begins to run at the expected 3100 RPM but then will eventually do the same thing and decrease RPM to ~2400. In Fan Control software, I can see the pump showing 3000 or so RPM but when I try to adjust it using manual control, it actually controls the radiator fans instead, whether it is connected to CPU_OPT or CPU_FAN.

 

[Paperdoc]

OK, that's not a surprise. Many mobos a few years ago assumed that ALL CPU coolers a were the new 4-pin design and gave you no option for the CPU_FAN header. That's what you have apparently, since the pump does run full speed. Exce4pt, of course, that it still drops to a lower sped after running a while. This confirms that such performance is built into the pump design, and there is nothing you can do to change it.

Further, the fact that changing the speed setting manually does change the rad fan speed but not the pup speed confirms this. The header IS using PWM control signals that impact the fan but not the pump. IF you want more info on all of this, try asking Tech Support at Deeopcool. There are now several reports showing this is a design feature. Maybe they can explain why?

 

[Dragos Manea]

CPU_FAN and CPU_OPT IS CONTROLLED BY CPU FAN, both of them, a few people reapeted that multiple times, stop wasting time to try and control opt because you will not control individually, it is TIED up to the cpu fan, if you want a completly independ control go for chasis 1 or chasis 2 for the AIO pump. Connect the AIO pump to the chasis 1 or 2 fan header, go into bios and set it up for full speed.

 

[SkyNetRising]

Connect the AIO pump to the chasis 1 or 2 fan header, go into bios and set it up for full speed.

And also switch fan regulation to DC mode, since it is 3pin fan connector.

 

[Paperdoc]

What Dragos Manea and SkyNetRising advise above will work to guarantee that the pump is being fed a constant 12 VDC at all times, That is exactly what my method does in a different way.

 

[AndyVG]

I have connected the pump to Chassis fan 1 and set to DC and full speed in BIOS as well as moved my back fan to CPU_FAN. This seems to create a lot of problems. My pump is constantly turning off, and is still not reaching 3100 RPM. my back fan also turns off when the pump does.

I think I'm just going to look into a new cooler brand at this point.

 

[AndyVG]

Any recommended cooler brands?

 

[Paperdoc]

I don't have a liquid cooler system, so I won't recommend. Others will. You might also consider an air cooler - simpler, and good ones certainly can handle most systems except for very high-power ones.

 

[CountMike]

I have connected the pump to Chassis fan 1 and set to DC and full speed in BIOS as well as moved my back fan to CPU_FAN. This seems to create a lot of problems. My pump is constantly turning off, and is still not reaching 3100 RPM. my back fan also turns off when the pump does.

I think I'm just going to look into a new cooler brand at this point.

Arctic Liquid Freezer II are simple but effective coolers with pump and radiator fans on one lead. no need to adjust pump speed, everything is powered just by CPU-FAN header. Various sizes and RGB and ARGB versions with excellent fans.

 

[Dragos Manea]

I never saw any mention, how is the radiator mounted? What is the position? Top, Front, Bottom?

 

[AndyVG]

I never saw any mention, how is the radiator mounted? What is the position? Top, Front, Bottom?

Top mounted radiator

 

[Dragos Manea]

Ok, then air bubbles are not the problem, the radiator is mounted correctly.

 

[AndyVG]

Just returned the deepcool. Purchased Lian Li Galahad II Trinity SL-INF 240mm and installed yesterday. Pump works perfectly so far and I can actually control the pump RPM via L-connect 3.

The LT520 and LT720 seems to work for some, and doesn't seem to work for others. Guess some motherboards are just not compatible. Maybe we all got defective units. Who knows

 

[weehamish]

How noisy is the new pump? I have a Corsair one with 3 presets and it's noisy on all 3... I'm use to air coolers and having total silence so not happy with this aio...