Background (the blog part)

In my previous personal builds, as well as some I’ve built for family and friends, I’ve used Asus ROG boards almost exclusively. I found them to be well made, reliable and I was very familiar with the ROG UEFI layout. There’s also the fact that as someone who does a lot of custom loop liquid cooling, I like to use coolant temperature sensors if they’re available on the motherboard, and almost every ROG board I’ve come across has them. If you’ve ever done custom loop cooling and haven’t used a coolant temperature sensor, I highly recommend it.

Warning – boring and technical coolant follows.

When liquid cooling a computer, your system’s fans don’t cool the CPU, at least not as directly as fans affect cooling in an air-cooled solution. Liquid has a much higher heat capacity than air, so it removes heat very efficiently as it flows through your system to the radiator or radiators. Radiators also have a huge surface area to then dissipate the heat from the coolant which then flows back into the system and removes more heat. Like the fins of an air-cooled heat sink, a radiator still needs some air flow across its fins to lower the temperature of the coolant as it flows through the coolant passages.

Without adequate airflow, a radiator will become saturated with heat and will no longer be able to dissipate the heat from the coolant. The lower the temperature of your refrigerant, the more heat capacity a given volume of refrigerant has and the more heat it will be able to transfer within the loop. So, in a liquid-cooled system, your fans are actually dissipating the heat from the radiator.

This means you don’t have to crank your fans up and down to match your CPU or GPU temperatures. You want your fan speed to be based on your coolant temperature. By having a motherboard that not only has a two-pin temperature sensor, but also allows fans to be controlled from usage, the readout from this sensor allows for this level of control. The way I’ve set it up in all my builds over the last few years is to connect the pump to the motherboard’s CPU header and then fix the rpm (on my current build, the D5 pump runs at a constant 3000rpm).

Most motherboards will alert you if they detect a malfunction there, and your pump is the only thing in your system you want to know right away if it stops. After that I just connect my fans to the other motherboard headers and then go into UEFI (or motherboard fan control software) and set the fan speeds based on the coolant temperature reading from the sensor. Using this method prevents the fans from constantly going up and down as your CPU temperatures rise and fall, but it also won’t skip the GPU’s effect on the loop.

We are now back to your regular blog-style programming.