Air cooler or liquid cooler: which should you pick?

What actually differs

Air is a block of metal sitting on the CPU with a fan blowing through it. Heat travels up the fins and gets blown away. One piece, nothing moving but the fan.

Liquid (AIO) is a sealed pre-built loop: a block on the CPU, a pump, hoses, and a radiator bolted to the case. The heat is carried somewhere else before being dumped — the real benefit is moving where the heat leaves, not necessarily moving more of it.

They are checked against different figures

This is why comparing the two head-to-head rarely helps — they run out of room in different places.

Air runs out of height. DeepCool AK400 is 155mm; Cooler Master MasterBox NR200P takes 153mm. Two millimetres short and the side panel will not close. The answer is a low-profile cooler such as Thermalright AXP90-X47, which is only 47mm.

Liquid runs out of radiator space. Arctic Liquid Freezer III 360 needs a 360mm radiator, which Lian Li Lancool 216 and NZXT H5 Flow can mount — but Montech AIR 100 ARGB takes 280mm at most, so you drop to DeepCool LE520 240mm and its 240mm radiator instead.

Is liquid really cooler?

It depends which against which. A 360mm liquid cooler does beat almost every air cooler. A 240mm one and a large twin-fan air cooler are in the same range.

The figure worth comparing is the TDP each is rated for. DeepCool AK400 (air) and DeepCool LE520 240mm (liquid) are both rated at 220W — the same manufacturer saying the two handle about the same heat.

Liquid’s clearer advantage is not temperature but room around the socket. There is no large block overhanging the memory slots and the top of the board, which makes assembly easier and airflow around the board better.

The parts people rarely mention

• A liquid cooler has a pump, and pumps fail. A dead fan can be replaced; a dead pump means replacing the whole unit, and a weakening pump usually gives no warning.
• Liquid is not automatically quieter. Pump noise is a low hum that is hard to tune out of a room, and some people find it more irritating than fan noise.
• Large air coolers are heavy and hang off the board permanently. Take one off, or lay the machine down, before transporting it.
• Wide air coolers can foul memory, particularly tall-heatspreader kits such as G.Skill Trident Z5 RGB DDR5 32GB (2x16GB) 6400 at 44mm.

So which one

1. 1An ordinary machine, modest budget, no overclocking → air. Done, no further thought needed.
2. 2A small case where a tall heatsink will not fit → two options: a low-profile air cooler, or a liquid cooler in the size the case accepts.
3. 3A power-hungry CPU you intend to overclock → a 280mm or 360mm liquid cooler, if the case can mount it.
4. 4A machine you want to leave alone for five years → air, because there is no pump to fail.