An active cooling solution for a PC is any cooling system that uses powered components, like fans or pumps, to move heat away from your processor and other hardware. This distinguishes it from passive cooling, which relies solely on metal heatsinks and natural airflow without any electricity-driven parts. Nearly every modern desktop PC uses some form of active cooling because today’s processors can generate well over 200 watts of heat, far too much for a passive heatsink to handle alone.
The three main types of active cooling are air coolers with fans, liquid cooling systems, and thermoelectric coolers. Each works differently, costs differently, and suits different builds.
Air Coolers: Fans and Heat Pipes
The most common active cooling solution is an air cooler mounted directly on top of the CPU. These coolers combine two technologies: heat pipes that pull heat away from the processor and fans that blow that heat into the surrounding air.
A heat pipe is a sealed metal tube containing a small amount of liquid. One end sits against the CPU. When the processor heats up, the liquid inside the pipe absorbs that energy and evaporates into vapor. The vapor travels through the pipe to the opposite end, which is connected to a stack of thin metal fins called a heatsink. There, the vapor cools, condenses back into liquid, and releases its heat into the fins. The liquid then flows back down to the hot end through capillary action (the same force that lets a paper towel soak up water), and the cycle repeats continuously.
The fan’s job is to push fresh air across those metal fins so the heat doesn’t just sit there. Without the fan, the heatsink would eventually reach the same temperature as the CPU and stop being useful. The fan keeps cooler air flowing across the fins, carrying the heat out of your case. This is the “active” part of the system.
Modern tower-style air coolers perform remarkably well. In testing by Tom’s Hardware, a mid-range air cooler like the Thermalright Peerless Assassin 120 SE handled a processor drawing over 200 watts better than much of its competition. Good air coolers are affordable, reliable, and have very few failure points since the only moving part is the fan itself.
All-in-One Liquid Coolers
All-in-one (AIO) liquid coolers are sealed, pre-filled units that use liquid coolant instead of heat pipes to transfer heat. They come as a single package with no assembly required beyond mounting.
An AIO has three key parts. A cold plate with a built-in pump sits on top of your CPU, similar to where an air cooler would go. The pump circulates coolant through flexible tubes to a radiator, which is typically mounted to the top or front of your PC case. Fans attached to the radiator blow air through its fins, cooling the liquid before it cycles back to the CPU.
The advantage of liquid over air is that water-based coolant absorbs and carries heat more efficiently than metal pipes alone, and the radiator can be placed far from the CPU, spreading the cooling work across a larger surface area. A 360mm AIO (one with three 120mm fans across the radiator) can handle the hottest consumer processors available. In recent testing, top 360mm AIOs kept high-end chips more than 10 degrees Celsius below their thermal throttling point, the temperature where the processor starts slowing itself down to avoid damage.
The trade-off is noise and complexity. The pump adds a faint hum, and some users find it noticeable at higher speeds. AIOs also cost more than air coolers of similar performance, and while rare, a pump failure means replacing the entire unit.
Custom Water Cooling Loops
A custom loop is the DIY version of liquid cooling. Instead of a sealed, pre-built unit, you buy each component separately and assemble the loop yourself. A complete custom loop requires water blocks (which sit on the CPU and optionally the GPU), a reservoir to hold extra coolant, a standalone pump, one or more radiators, fans, fittings, tubing, and coolant.
Custom loops offer several advantages over AIOs. You can cool both your processor and graphics card in the same loop. You can use larger or multiple radiators for greater cooling capacity. And you can choose higher-quality pumps that run quieter or last longer. Many builders also choose custom loops for aesthetics, using colored coolant and transparent tubing.
The downsides are significant. Custom loops are expensive, often costing several hundred dollars for parts alone. They require periodic maintenance, including draining and refilling the coolant every 6 to 12 months. And any mistake during assembly, like a loose fitting, risks leaking liquid onto your components. Custom loops are best suited for enthusiasts who enjoy the building process and want maximum thermal performance or a specific visual look.
Thermoelectric Coolers
Thermoelectric coolers (TECs) use electricity to directly transfer heat from one side of a ceramic plate to the other. When current flows through the device, one side gets cold while the opposite side gets hot. You place the cold side against the CPU and attach a heatsink or liquid cooler to the hot side to dissipate the waste heat.
The appeal of TECs is that they can cool a component below the ambient room temperature, something no fan or liquid cooler can do. This makes them interesting for extreme overclocking.
In practice, TECs have serious drawbacks for everyday use. They’re roughly one-quarter as efficient as conventional cooling methods, achieving only 10 to 15 percent of their theoretical maximum efficiency. Every watt of cooling a TEC provides generates additional waste heat from its own power consumption, which means the hot side of the device actually has to dissipate more total heat than the CPU alone produces. As the temperature difference between the cold and hot sides grows, the module becomes even less efficient because heat conducts back through the device itself. For most PC builders, TECs create more problems than they solve and remain a niche option.
Choosing the Right Fan Type
Regardless of which active cooling solution you pick, fans are involved. Two specifications matter most when selecting them: airflow (measured in cubic feet per minute, or CFM) and static pressure.
High-CFM fans move large volumes of air and work well as case fans, where there’s minimal obstruction. Static pressure fans are designed to push air through tight spaces, like the dense fins of a CPU heatsink or a liquid cooling radiator. If you’re using a fan on a cooler or radiator, you want one optimized for static pressure. For open case ventilation, standard airflow fans work fine.
Keep in mind that the CFM numbers printed on fan packaging are measured with zero airflow restriction, so real-world performance is always lower. A fan with strong static pressure will come closer to its rated airflow in actual use because it can maintain performance even when pushing against resistance.
Which Solution Fits Your Build
For most users building a general-purpose or gaming PC, a quality tower air cooler handles anything up to and beyond 200 watts of CPU heat output. They’re the most cost-effective, easiest to install, and most reliable option. A 240mm or 360mm AIO makes sense if you’re running a high-end processor at full power, want a cleaner look inside your case, or have limited clearance above the CPU socket for a tall air cooler. Custom water cooling is for enthusiasts who want to cool both the CPU and GPU with a single system and don’t mind the maintenance commitment. Thermoelectric cooling is reserved for specialized overclocking experiments where sub-ambient temperatures are the goal, not for daily use.