Like any powerful piece of PC hardware, the CPU generates heat when in operation and needs to be properly cooled to achieve maximum performance.
As Mark Gallina, System Thermal & Mechanical Architect at Intel explains, “During normal operation, the transistors inside a CPU convert electrical energy into thermal energy (heat). This heat increases the temperature of the CPU. If an efficient path for that heat doesn’t exist, then the CPU will exceed its safe operating temperature.”
But what’s the best way to keep your CPU operating at the ideal temperature? There are many ways to cool a processor, but most desktops and laptops use an air- or liquid-based cooler.
We’re going to talk about liquid cooling vs air cooling: how they work, the pros and cons of each, and which might be right for your setup.
How a CPU Cooler Works
Both air and liquid CPU coolers operate on a similar principle, and both do essentially the same thing: absorb heat from the CPU and redistribute it away from the hardware.
The heat generated by the processor itself is distributed to the metal lid of the CPU, called the Integrated Heat Spreader (IHS). The heat is then transferred to the baseplate of the CPU cooler. That heat is then distributed, either by liquid or via heat pipe, to a fan, where it is blown away from the cooler and eventually away from the PC.
Though the underlying mechanics are similar, the two methods achieve this heat redistribution in very different ways.
Let’s start with an air cooler.
Cooling with Air
In an air cooler, the heat is transferred from the IHS of the CPU, through the applied thermal paste, and into a conductive baseplate that is usually made from copper or aluminum. From the baseplate, that thermal energy moves into the attached heat pipes.
The heat pipes are designed to conduct heat from one location to another. In this case, the heat moves to a heatsink that is elevated off of the motherboard, freeing up space for other components, such as RAM. These pipes deliver the energy in the form of heat to the thin metal fins that make up the heatsink. These fins are designed to maximize exposure to the cooler air, which then absorbs the heat from the metal. An attached fan then pushes the warm air away from the heatsink.
Less common than a standard air cooler, but similar in theory, is what’s called a passive cooler. These rely on a specially designed heatsink to absorb and redistribute heat without the use of a fan. These can be useful in builds where lower acoustics are a priority, but most gaming computers use an air or liquid cooler.
The effectiveness of an air cooler can vary, depending on factors such as the materials used in construction (copper is more conductive than aluminum, for example, though aluminum is cheaper) and the size and quantity of fans attached to the CPU heatsink. This explains the variation in the size and design of air-based CPU coolers.
Larger air coolers usually dissipate heat better, but there isn’t always room for a bulky cooling solution, especially in a small form factor PC.
We’ll further explore the advantages of air cooling, but first, let’s go over liquid cooling for the sake of comparison.
Cooling with Liquid
As with air coolers, there’s a wide selection of available options, but most fall into two categories: All-in-One (AIO) coolers, or custom cooling loops. We’ll mostly be focusing on All-in-One (AIO) coolers here, though the fundamental principles of how the liquid cools the CPU are the same in both.
Similar to air cooling, the process starts with a baseplate that is connected to the IHS of the CPU with a layer of thermal paste. This allows for better heat transfer between the two surfaces. The metal surface of the baseplate is part of the waterblock, which is designed to be filled with coolant.
The coolant absorbs heat from the baseplate as it moves through the waterblock. It then continues to move through the system and upward through one of two tubes to a radiator. The radiator exposes the liquid to air, which helps it cool, and fans attached to the radiator then move the heat away from the cooler. The coolant then re-enters the waterblock, and the cycle begins again.
Which Is Right for You?
Both cooling options are highly effective when properly implemented, but excel in different circumstances. Here are a few factors to consider when making your choice.
Price can vary substantially depending on the features you’re prioritizing. Generally speaking, though, air coolers cost less due to their more straightforward operation.
There are entry-level and premium versions of both. A premium version of an air cooler might have a larger heatsink, better fans, and provide different aesthetic options. A high-end All-in-One (AIO) liquid cooler might have a larger radiator, and offer a mix of aesthetic and functional customization, such as software to control fan speeds and lighting.
Both air and liquid CPU coolers are priced across a large spectrum, depending on the features you’re looking for.
Ease of Installation
Though an All-in-One (AIO) liquid cooler is often more complex to install than a standard air cooler, it’s still fairly straightforward. Most consist of only the waterblock, the two hoses that cycle the coolant, and the radiator. The extra steps involve attaching the waterblock, which is a process similar to installing an air cooler, and then attaching the radiator and the fans in such a way that the excess heat can easily exit the PC. Since the coolant, pump, and radiator are self-contained in the apparatus (hence the name “All-in-One (AIO)”), it requires very little oversight or maintenance after installation.
Installing a custom loop, on the other hand, requires more effort and education on the part of the builder. The initial installation process might be more time-consuming, but the added flexibility allows for significantly more customization and the option of including other components such as a GPU into the loop if desired. These more complex custom loops can also support builds of all shapes and sizes when properly implemented.
Air coolers can be bulky, but that bulk is limited to one area, as opposed to being distributed across your system. With an All-in-One (AIO), on the other hand, you’ll need space for the radiator, and will also need to factor in issues like proper orientation and alignment of the waterblock and coolant tubes.
That said, if you’re working in a smaller build, a bulky air cooler might not be the best option. A low-profile air cooler or an All-in-One (AIO) with a small radiator could be a better fit. When planning your upgrade or choosing your case, ensure that you have sufficient space for your cooling solution of choice and that your case supports the hardware you’ve selected.
Liquid cooling, especially when using an All-in-One (AIO), tends to be quieter than the fan on a CPU heatsink. Again, this can vary, in that there are air coolers with fans specifically designed to reduce noise, and fan settings or fan selection can impact the amount of noise generated. Overall, though, liquid cooling tends to generate less sound, as the small pump is usually well insulated, and radiator fans tend to run at lower RPM (revolutions per minute) than those on the CPU heatsink.
If you’re serious about overclocking, or plan on undertaking CPU-intensive tasks like rendering video or streaming, liquid cooling might be the best choice.
According to Mark Gallina, liquid cooling more “efficiently distributes heat over more convection surface area (radiator) than pure conduction, allowing for reduced fan speeds (better acoustics) or higher total power.”
In other words, it’s more efficient, and often quieter. If you want the lowest possible temperatures, or if you’re interested in a quieter solution and don’t mind a slightly more complex installation process, liquid cooling is probably the best option.
Air coolers are quite good at relocating heat away from the CPU, but keep in mind that heat is then dispersed into the case. This can raise the ambient temperature of the system overall. Liquid coolers do a better job of relocating that heat outside of the system via the fans on the radiator.
Make Your Choice
So, back to the original debate: Liquid cooling vs air cooling. Which is better?
The answer depends on how you use your computer and the performance and workloads you expect to encounter.
If you want almost silent operation, the most efficient cooling, and don’t mind a potentially higher price tag, liquid cooling will fit the bill.
If you’re looking for a solution with more entry-level pricing and simple installation at the potential expense of peak performance or acoustics, air cooling is an easy recommendation.
Consider how you use your PC, and how you plan to use it in the future when making your choice. Though both are excellent solutions, they are designed for slightly different use cases. It’s up to you to decide which is a better fit for how you use your computer.