[Reference] Logical configuration guide of Asetek AIOs at a Hardware Level (Corsair, NZXT, CM, etc)

[For Science!]

Hi All,

 

I decided to create this thread about how common AIOs such as Corsair H-series and the NZXT krakens should be set up in my opinion. There have been an influx of AIO related questions on this sub-forum lately and so I thought one post to refer to will save me time in the future. Personally I wouldn't be salty if the forum got sub-divded into AIO-related and custom loop related, but thats just my opinion (@W-L?).

 

Feel free to contribute/disagree/agree, but I largely will stand by my statements below since this is ultimately merely my way of doing things.

 

Which AIO should I get?

A lot of the time, a question comes up asking which AIO is better than another AIO. What's usually missed is that a lot of the popular AIOs are actually all made from the components supplied by Asetek, which are then branded by the respective companies to give their individuality. Therefore large in large which AIO you get does not really matter if you like the looks, and what often sets AIOs apart is the fan included and the warranty information. There are minor differences from pump generation to generation, and usually a newer product tends to perform slightly better (and also may last longer since it hasn't been sitting around permeating fluid)

 

https://www.asetek.com/desktop/do-it-yourself/

 

How big should my AIO be?

This is similar to that of how many radiators some should get for a custom loop. Generally speaking, a 120 mm AIO is a poor value for money. Not only do they perform on par with a low-mid tier air cooler, they are typically louder since they have a pump and a fan. The only place where a 120 mm AIO makes sense is in extremely small form factor PCs where the alternative may be a low profile CPU cooler, and even then it is debatable whether the AIO is a good choice.

 

Generally speaking 240 mm and up is what I would recommend. Theoretically the bigger the better, and so if your case can accommodate larger radiators, a 360 mm AIO will perform better (or at least in terms of noise-normalized performance).

 

It is near impossible to predict what temperatures you will get with a certain AIO and component. This is because your component temperature will depend on many parameters such as voltage, ambient temperature, fan speed, air flow, thermal paste, delid, dust, etc etc. 

 

In water cooling, fluid temperature will dictate your cooling potential. Fan curves should be based on fluid temperature, not CPU temperature or GPU temperature.

I say AIOs are the gateway drug into custom watercooling, it is easy to plug an AIO in without really knowing what you're getting into. First of all, watercooling is still aircooling. The heat from the component is moved away from using liquid, moved to the radiator that has a large surface area, and then this is cooled by air from the fans. The only difference between watercooling and aircooling is where the heatsink array is, in air-cooling this is directly in contact with the component, whereas in watercooling it is put in a remote location and the energy is transported to the location via fluid.

 

This implies one thing: there is no point increasing the fan speed of an AIO (or in a custom loop) if the fluid is not hot. Fan curves should be based off fluid temperatures in the watercooled systems since you are ultimately trying to keep the water cool, if the water is hot, you want to increase the fan speed to cool it down. If the water is cold, then pushing more air through the radiator will have no effect whatsoever.

 

In a custom loop it is typical to plug in a 2-pin temperature sensor and feed this into either the motherboard directly or through an external device such as an Aquaero. This is not possible in AIOs, but thankfully most AIOs from Asetek have fluid temperature sensors built into them

 

If your pump has fan headers coming off them. Plug your fans there, not the motherboard. These fans should be 4-pin PWM regulated fans.

While the AIO pump may have temperature sensors in them for the fluid, your computer does not know anything about them by default. This is why the fans should be connected to the AIO and not the motherboard. NZXT and Corsair AIOs have 4-pin fan headers which should be populated with 4-pin PWM regulated fans. If you plug a 3-pin fan, it will likely spin at full speed and not be regulated (which is because a 4-pin fan header works with a constant 12 V voltage, which is max speed on DC mode). 

 

If you plug your fans into the motherboard, then the fan will be regulated via the CPU temperature, which makes no sense if you were cooling a GPU, but even for cooling a CPU is not efficient. In a heaviliy overclocked system going for 75 degrees is not unusual even on water. However more motherboards have safety features that send all fans to 100% rpm when the CPU goes over some critical temperature (typically 75 degrees). This means that you can get fans going to turbo mode, despite the water temperature in the AIO being quite cool. Meaning you get all the noise with little gain in temperatures since you are probably limited by the IHS's ability to dissipate heat to the cold plate.

 

Asetek pumps are not designed to be voltage regulated. They should receive a constant 12 V supply

Most Asetek AIOs have a 3-pin fan header to power the pump (some have SATA power, in which the 3-pin fan header only reports back the rpm). These should be plugged into a fan header on the motherboard and set to DC mode and 100% fan speed at all temperatures. Another way which would achieve the same result is to set it on PWM mode since that is technically a constant 12 V signal, I prefer the former. Pump speed is not to be regulated via the BIOS and failure to do so can significantly impact the lifetime of the AIO.

 

CPU_FAN header, or AIO_PUMP header?

Which header is pretty much up to you, modern motherboards are capcable of delivering enough power on any header for your typical AIO. Having said that there are a few considerations.

 

If you plug the AIO into the CPU_FAN header then should the AIO fail, you will be warned on boot with a cpu_fan error, so it is a nice way to have a in-built security to check the AIO is working. However CPU_FAN headers typically have a fairly standard fan curve associated with it and so this will need to be changed in the BIOS to achieve a constant 12V  power supply as mentioned in the section above.

 

If you do not plug anything into your CPU_FAN header you will be greeted by a cpu fan error on boot, since this is a built in safety feature to make sure you don't kill a CPU with no cooling. This can be overrided in the BIOS by disabling monitoring of the CPU_FAN rpm. Plugging the AIO into the AIO_PUMP header is convenient because typically they have a "fan curve" associated with them that supplies the 12 V automatically. The obvious downside is that if the AIO dies, the computer will happily let itself toast until thermal shutdown (since the AIO_PUMP has no inbuilt warnings)

 

Fan/pump control should be down through the respective software, not the motherboard (CLink, NZXT cam, etc)

If you add the information above: pump needs a constant 12V, fluid temperatures should dictate the fan speed, and the pumps are plugged into the pump block; there is only one logical conclusion - fan and pump control cannot be done through the BIOS and can only be done through software for AIOs. This means using the utilities that come with the AIO to set up the custom fan curves if you wish. However this is an inconvenience for Linux users since these software tend to have limited supported outside of windows. Having said that the AIOs have inbuilt fan curves based on fluid temperatures, which at least for the Corsair H100i v2 that I used, is sensible. However this makes it even more important that the fans are plugged into the pump headers and not the motherboard since otherwise you will not leverage the fluid temperature readings.

 

If you find your pump noisy/clicky then it is likely to be air trapped in the pump. Please try the instructions in the video.

 

 

Where you place your radiator largely doesn't matter, but ideally a portion of it should be above the pump block

Where you place the radiator tends to have limited impact, but as per the video above, it is a good idea for a portion of the radiator to be higher than the pump block so air can stay there and not recirculate. My personal preference is to have the radiator mounted on top as exhaust so that the heated air exits the case while allowing to maintain an unobstructed intake.

 

Is an AIO just filled with water?

No, AIOs are filled with a mixture of propylene glycol and ethylene glycol + water to combat the galvanic corrosion that is happening between the aluminium radiator and the copper block. This is also likely why AIOs get clogged after a few years.