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Is it worth buying a 120mm AIO liquid cooler?

A single 120mm radiator provides plenty of cooling power, but we explore whether its enough to keep the most powerful processors in check.

A be quiet! 120mm AIO cooler

I’d been looking forward to a group test of 120mm AIO liquid coolers for a while. I’d heard plenty of comments online about them being pointless compared with larger models with bigger radiators, but what surprised me was testing NZXT’s Kraken 120 when Intel launched its 12th-gen CPUs recently.

It actually managed to tame the mighty Core i9-12900K at stock speed, which is significant news for small form factor systems. It means that while many small or low-profile air coolers would struggle, using a 120mm AIO liquid cooler could be sufficient and would also dump the heat straight out of your case via the radiator.

These coolers are cheaper than larger models and easy to install, especially in cases with limited cooler height limits. There is a flip side to these positives, though, which relates to radiator size. The key benefit of larger radiators – and this applies to custom liquid cooling too – is that they have a much greater ability to dissipate heat.

This is due to their larger heatsink surface area and greater number of fans, which combine to offer better cooling at lower noise levels, as the fans don’t need to spin as fast to offer similar or better cooling. In addition, there’s more coolant in the loop, as radiators have large cavities for it to flow through them.

The high heat capacity of coolants means they can absorb a lot of heat before they actually warm up – the more coolant in the loop, the longer it takes before the fans need to spin up. As a result, larger AIO liquid coolers will remain quieter for longer.

While a 120mm AIO cooler can cope with a Core i9-12900K under full load, it will likely need to spin up its fan to full speed quickly to deal with the heat. A larger liquid cooler won’t have to do this, even if the pump, flow rate and contact plate are identical. If you’re using a less powerful CPU, though, such as the Core i5-12600K, a 120mm AIO liquid cooler can clearly do the job fine.