What Is an AIO Cooler and How Does It Work? | Liquid Cooling Explained

An AIO cooler is a sealed liquid cooling loop that moves CPU heat into a radiator, where fans push it out of the case.

A tower air cooler eventually hits a wall: the bigger the heatsink, the more it fights your case for space, and the harder it is to move heat off a chip pushing 250 watts. An AIO cooler sidesteps that by carrying heat away in liquid instead of metal, which is why you see them in so many high-end builds.

CORSAIR describes an AIO as a sealed liquid cooling system with a pump head, radiator, tubing, and fans. The loop arrives pre-filled and sealed, so you never source or mix coolant — you mount it and go.

The Four Parts Of The Loop

Every AIO is a closed circuit that starts at the CPU and ends at the radiator, and each part has one job.

• Pump head / water block: Mounts directly on the CPU, pulls heat out through a copper cold plate, and pushes warmed coolant out.
• Tubing: Carries the warmed coolant to the radiator and the cooled coolant back.
• Radiator: A finned aluminum block that releases heat into the passing air.
• Fans: Push air through the radiator fins and exhaust it out of the case.

That’s the whole system. No reservoir to top off, no distilled water runs, no leaks to chase as long as you leave the factory seal alone.

How An AIO Cooler Moves Heat, Step By Step

The cycle repeats the entire time your PC is on, and it never stops moving heat as long as the pump is running.

1. Your CPU generates heat under load.
2. The cold plate on the pump head absorbs that heat and passes it into the coolant.
3. The pump circulates the warmed coolant through the tubing to the radiator.
4. Fans blow air across the radiator fins, releasing the heat into the surrounding air.
5. The cooled liquid returns to the pump and starts the trip again.

Because liquid carries heat more efficiently than air alone, an AIO can dump heat at the radiator rather than right next to your CPU socket — which also keeps your motherboard and RAM breathing easier.

What Size AIO Fits Your Build?

Radiator size is the number one spec to get right, because your case has to physically hold it and your CPU has to be worth cooling with it.

CORSAIR sets 240mm as the fit for most mid-tower cases and points 360mm at high-performance CPUs and full-tower builds. If you want a 240mm unit and want to skip the guesswork, our tested roundup of 240mm AIO coolers covers the models worth your money.

How To Install One (And What To Watch For)

1. Power off the PC and unplug it.
2. Remove your old cooler and clean the CPU surface.
3. Install the backplate or bracket for your socket.
4. Mount the radiator and fan(s) — front intake or top/rear exhaust works best.
5. Apply thermal paste if it isn’t already pre-applied.
6. Set the pump head evenly on the CPU and tighten screws diagonally, a little at a time.
7. Connect the pump, fan, and RGB cables to the right motherboard headers. Some models, like the TITAN 360 RX RGB, tie into iCUE software for control.

You’ll know it worked when the pump lights up, fans spin, and your CPU idles noticeably cooler than it did on the old cooler.

Two caveats matter before you buy. Second, because AIOs are sealed, CORSAIR’s TITAN 360 RX RGB product page confirms the loop is factory-sealed — don’t open it or try to refill coolant. CORSAIR’s own explainer makes the same point: it’s pre-filled, so leave it alone.

FAQs

Do AIO coolers leak?

Sealed AIOs are far less leak-prone than custom loops because there are no user-made fittings.

How long does an AIO cooler last?

The fans and radiator usually outlast the pump, so if temperatures creep up years later, the pump is the first thing to check.

Is an AIO better than an air cooler?

Not automatically. Air coolers can match a 240mm AIO on many CPUs for less money. AIOs win on space, clearance for tall RAM, and heat capacity at 280mm and 360mm — so pick based on your case and CPU, not hype.