What Is an AIO Cooler and How Does It Work? | The Heat Loop

Modern desktop CPUs put out far more heat than a simple aluminum block and fan can handle at full load. If you’re wondering what an AIO cooler is and how it works, the short version is this: it’s a sealed liquid loop that combines the pump, cold plate, radiator, tubes, and fans into one closed unit. It pulls heat away from the processor far more efficiently than air alone, which is why you see them on high-end gaming and workstation builds.

How Does an AIO Cooler Work?

An AIO cooler moves heat from the CPU into a liquid, carries that liquid to a radiator, and lets fans push the heat into the room air. The loop is fully sealed, so you never need to refill it or bleed air out.

The heat path looks like this:

1. The CPU’s metal lid presses against a copper cold plate, and heat soaks into the plate.
2. Liquid absorbs that heat and is pumped out of the water block.
3. The warmed liquid travels through the tubes to the radiator.
4. Radiator fans blow air across the fins, dumping the heat into the room.
5. The cooled liquid returns to the cold plate, and the loop repeats.

That’s the whole job. The pump is the only moving part that matters, and the radiator size controls how much heat the loop can shed.

Installing an AIO Cooler: What the Official Guides Say

Installing an AIO cooler comes down to five steps: verify socket support, mount the backplate and standoffs, mount the radiator, set the pump head, and connect the headers. The exact bracket kit depends on your motherboard’s CPU socket.

1. Check that the cooler’s mounting hardware supports your socket; Corsair’s Intel guide says to confirm support before you start.
2. Mount the backplate and standoffs for your socket, following the included bracket method.
3. Mount the radiator with its fans already attached, positioned with the tube side not at the top of the loop.
4. Place the pump head over the CPU, align it with the standoffs, and hand-tighten the thumbscrews in a criss-cross pattern.
5. Connect the pump to the CPU_FAN header and any required USB 2.0 header, plus any PSU-powered connectors.

Two warnings from Corsair’s official documentation: Corsair’s AM4 installation guide warns that overtightening the thumbscrews can damage the retention hooks, and its radiator guidance says to keep the pump below the highest point of the radiator where air collects.

Sizing and Compatibility: Which AIO Fits Your Build?

An AIO’s radiator length is the main spec, with 120mm, 240mm, and 360mm sizes fitting different cases, and the mounting block must match your CPU socket. Most current models cover both Intel LGA 1700 and AMD AM5, and many include brackets for older LGA 115x sockets and AM4.

For most mid-tower builds, a 240mm radiator is the sweet spot—see our roundup of the best 240mm AIO coolers for the models we’ve tested. Before buying, measure your case’s radiator clearance against the cooler’s full radiator length and thickness, plus fan height. The table below shows how real models from NZXT vary in size, fan speed, and noise.

For most builders, a 240mm AIO offers the best balance of cooling, noise, and case fit, while 360mm models are worth it only for the hottest CPUs.

FAQs

Which is better: an AIO cooler or an air cooler?

AIO coolers generally cool better under load and take up less room around the CPU socket, but air coolers are simpler, cheaper, and have no pump to fail. On mid-range CPUs, a good tower air cooler often matches a 240mm AIO, while a 360mm AIO pulls ahead on high-end chips.

How long does an AIO cooler last?

Most AIO coolers last five to seven years before the pump wears out or fluid gradually permeates the tubing, based on typical manufacturer ratings. When the pump fails, the CPU temperature spikes immediately rather than the unit leaking, so the fix is replacing the cooler itself.

Does the pump need to be above or below the radiator?

Keep the pump below the highest point of the radiator. Air collects at the top of the loop, and a pump sitting at that highest point pulls air instead of liquid, which hurts cooling and shortens pump life. The tube side should not be at the top of the loop either.