When building a PC, the importance of cooling cannot be overstated. It's not just about the performance you leave on the table by picking a weaker CPU cooler. Insufficient cooling can even stop you from using your computer (in some cases), or worse, damage your CPU if ignored for a while.

Modern CPUs are engineered to run hot out of the box, to maximize performance without relying on overclocking. If you intend to indulge in demanding games or intensive productivity applications though, you can't skimp on the CPU cooler. Whether it's air or liquid cooling you prefer, you might need to replace your existing cooler in a few telltale situations.

5 You're rocking a stock or cheap cooler on a powerful CPU

Modern CPUs are toasty even at idle

Over the years, we've seen CPUs become denser and more power-hungry. As power requirements increase, so do the heat output and operating temperatures. Even at idle workloads, when you aren't running a game or program, and simply have a few browser tabs open, CPU temperatures can easily run into the 50s Celsius — and that's on my Ryzen 7 5700X with a 240mm AIO liquid cooler.

Stock coolers might be enough for casual gamers and home office users, but if you're doing anything more than that on even a 6-core CPU purchased in the last 4 years, you'll need a decent aftermarket cooler. If you're buying an air cooler, I'd advise you to skip over models like the Cooler Master Hyper 212 that were once highly regarded, but fare much worse in the face of similarly-priced, better-performing options like the Thermalright Peerless Assassin 120.

If you're already noticing lower performance than your particular CPU is capable of, a cooler upgrade might be overdue. Just ensure you have also ticked off other items on the list when it comes to PC cooling — a case with good airflow, enough case fans, and optimized fan curves.

4 Your CPU cooler is too old

It's time to retire at some point

It's also possible that your CPU cooler is just too old to keep up with the demands of modern processors. It might have been a beast when you first bought it, but an aging cooler is doing your CPU no favors. You might start noticing the signs of an obsolete cooler in your daily usage, which can include the following:

• The fan bearings of your air cooler have worn out, leading to noisier fans.
• One or more fans might have broken down, causing strange, screeching noises.
• Your liquid cooler is unable to keep CPU temps low even at idle workloads.
• Your cooler fans are always running full-blast (which could also be due to unoptimized fan curves).

In most cases, you'll realize that your old cooler isn't holding up within a few days of installing it on your new CPU, but it's also possible that you've been ignoring the signs. In any case, it's best to replace your cooler as soon as you realize that it's faulty, broken, or simply not up to the task.

3 Your CPU always runs hotter than it should

Something's not adding up

This scenario mostly occurs when you build a new PC and start observing unusually high CPU temps. At first, you might think of re-applying the thermal paste, trying a new type of thermal paste, re-seating the heatsink, or optimizing the fan curve. Once you've eliminated every other possibility and still notice high temperatures — think mid or high 90s Celsius during gaming — you have to consider that you made a bad choice when picking the cooler.

Of course, a cooler replacement should be the next step only if you already have good airflow in your case, and your particular CPU model isn't known to run unusually hot. You can search online to gain perspective from other users with the same chip, and figure out which CPU cooler you need to buy next. This activity should ideally be done during the planning process for the build, but you can't go back in time, can you?

2 Your CPU is thermal throttling

It's begging for help

A colossal symptom signaling insufficient CPU cooling is thermal throttling — a tendency of a CPU to lower performance when its temperature reaches TJMax or maximum operating temperature. This can manifest in various forms — you'll either notice stuttering in games, program crashes, BSODs, or, in the worst cases, instant system shutdowns. The CPU is designed to protect itself from overheating by any means possible.

You might suspect the CPU in this case, but they're sturdy pieces of silicon, and very rarely fail. The more likely culprit is the CPU cooler. It's unable to keep the CPU below its TJMax, and thus, unable to prevent thermal throttling. You could also look at your CPU fan curve, and try to increase the fan speed at or near the TJMax temperature. But, if that doesn't help, the last resort is to replace the cooler.

Replacing the thermal paste or undervolting the processor might help avoid throttling, but they could just prove to be temporary solutions. Besides, willingly lowering performance to avoid overheating sounds like a step in the wrong direction instead of admitting the obvious — the CPU cooler just isn't the right fit.

1 You intend to overclock your CPU

Desperate times, desperate measures

If you've decided to overclock your processor, you'll need to be absolutely sure that your CPU cooler is up to the task. If you've never overclocked your CPU before, you might be chugging along with a cooler that's enough for your CPU's stock settings. For an overclocked CPU, however, you need serious cooling, especially if you're pushing a modern 8-core CPU or something even more powerful to its limits.

CPUs like the Core i9-14900K are known to throttle even when running with some 360mm AIOs, unless you manually limit the maximum power supplied to the CPU in the BIOS. While this is an extreme case, you'll almost always need a pretty powerful liquid cooler if you're overclocking a high-end chip. Enthusiasts who are looking to push their processors to new heights should look at liquid metal TIM or, on the extreme end, liquid nitrogen cooling.

Don't skimp on cooling when building a PC

The CPU cooler is one of the components you shouldn't skimp on in a build. Just like the power supply, SSD, and motherboard, the CPU cooler has a huge impact on both the performance and the general well-being of other components. If you're putting together a general-use system, or something for kids or office use, then you might be okay with a stock cooler. For gaming or productivity, however, a solid aftermarket cooler is recommended.