Air versus liquid has been debated for decades within PC hardware circles. Both have merit, and can be incredibly effective if implemented properly with quality components, but one implementation of liquid cooling is particularly problematic. It completely tarnishes the good name of AIO coolers everywhere, and I can't believe people still use them.

CLC solutions with radiator sizes of 120mm or 140mm are simply way too small to adequately cool modern CPUs for performance workloads. Unless you're under space constraints, there's simply no reason to use one, and it's high time everyone stopped buying them for good.

Why liquid cooling is effective in the first place

Large thermal capacity paired with low acoustics

Just generally speaking, water has a much higher thermal capacity than air does, and this is why liquid cooling is so effective for cooling computer components. It pumps water from the cold plate that has direct contact with the CPU's integrated heat spreader (IHS), through to a radiator that's in a different part of your case, which has fans blowing through the small finned channels that are carrying the liquid. These small fins increase surface area, and in turn, the cooling potential. The main appeal is that you're taking the heat away from the source and dissipating it elsewhere.

At the high end, air cooling is simply not a match for liquid, and it comes down to that thermal capacity. The amount to which an AIO liquid cooler can dissipate heat doesn't come down to the quality of the cold plate, the pump, the reservoir, nor the fancy RGB on the pump assembly. It comes down to the radiator's surface area, and small ones are extremely limited in the thermal load they can handle.

Why small liquid coolers are bad

And what you should buy instead

AIOs with large radiators can keep the warmest of components cool, and do it quieter than an air cooler could, but AIOs with small radiators are mostly inadequate. A 120mm radiator simply doesn’t have enough surface area to keep up with modern CPUs, especially those with higher boost frequencies and aggressive power limits.

Even a mid-range chip can saturate a small loop, causing the coolant temperature to climb rapidly, which forces the fan and pump to spin to their limits to compensate. The result is a warm, often throttling CPU, and one noisy PC.

You also take on all the same reliability issues that come with owning a AIO liquid cooler. CLCs with small radiators still have all the complexity of a CLC with a large one: a pump that can fail, tubes and barbs, and fluid that evaporates over time. The reward for this risk is usually better performance, but 120 and 140mm radiators just leave you in a lose-lose situation most of the time.

If you have the space, always size up. A 240mm or 280mm AIO is the minimum sweet spot for most modern CPUs, and 360mm units are ideal if you’re running something particularly warm, or plan to overclock. If you prefer to stick with air, high-end dual-tower coolers like the Noctua NH-D15 can perform neck-and-neck with many 240mm liquid coolers, without the risk of pump failure.

When a small AIO can make some sense

They're not completely without merit

There are still situations where buying a compact AIO is the right call, but they're pretty niche. Most of the time, they're thrust on unsuspecting first-time builders or pre-built buyers, who can't be expected to understand that just because it says "liquid cooling", doesn't mean it's actually better.

If you’re building in a small form factor case where space is tight and vertical clearance is limited, a 120mm or 140mm AIO can sometimes be the only viable option. SFF chassis can often leave no room for tower coolers of any kind, and even the stock cooler might not fit. A small AIO mounted to the side or rear panel can help keep temperatures under control, but what's underneath that cold plate matters just as much.

Handling the thermal load of a high performance, high TDP CPU in a small chassis will always be a challenge, no matter what sort of cooler you use. A small AIO can actually be a great choice for a CPU that isn't going to guzzle voltage. 65w chips, like the Core Ultra 5s and Ryzen 5s of the world, can be cooled adequately enough, especially if you apply an undervolt on top of that.

Low-profile air coolers might be better anyway

It all depends on the scenario

If your build is small enough that you’re considering a 120mm AIO, you might be better off with a low-profile air cooler instead. Coolers like the Noctua NH-L12S can deliver surprisingly competitive thermal results without introducing the potential failure points of a liquid loop. It's all dependent on airflow, the type of case you have, and what the thermal load of other components in your rig are. They might not be as flashy as RGB AIOs, but the long-term reliability and simplicity may make them a better fit for many compact systems.

Small AIOs should be forgotten about for full size rigs

Liquid cooling isn’t inherently better. Radiator size and airflow are what actually matter, and in most scenarios, a 140mm or smaller AIO just doesn't cut it. It might seem like an upgrade over air cooling, but it rarely is. It adds complexity, cost, and potential failure points for a level of cooling that isn't adequate for most modern CPUs.