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5 Best Air CPU Coolers for 2021

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Best Air CPU Coolers
Best Air CPU Coolers

When you’re looking to cool a more demanding CPU like the Ryzen 7 5800X or 5900X, or the Intel i7 or K series variants, you might want to consider a high-end air cooler. These CPU coolers offer the advantage of lower noise and increased reliability over ‘all in one’ liquid cooling systems thanks to their large fans and simple but effective design.

We decided to obtain a range of examples from the market leaders Noctua and BeQuiet! In order to assess them for compatibility, ease of fitment and take a look at the performance they offer – to give you a comparison of the best air coolers for high-end PC builds in 2021.

Starting out with more compact options we take a look at the Noctua NH-U12S, and the bequiet! Dark Rock 4. These coolers offer the best compatibility and clearance thanks to relatively compact designs. The NH-U12S uses a 120mm Fan whilst the Bequiet Dark Rock 4 uses a 135mm fan.

Then there’s the option of splitting the difference between the compact and dual fan coolers, the Noctua NH-D15S, which uses just one 140mm fan and a split heat sink – offset to assist in compatibility.

Finally, we pit the two dual-fan options against each other: the Noctua NH-D15 is the most powerful air cooler on the market, and the huge heat sinks and pair of 140mm fans promise great things. Up against it is be quiet’s Top offering, the Dark Rock Pro 4. Again with two fans but differing in size, this cooler blends great looks with low noise.

Best Air CPU Coolers – Our Recommendations

1. Noctua NH-U12A

Noctua NH-U12A Box

The Noctua NH-U12A is a high-performance tower cooler with 7 heat pipes, a single fin stack, and a pair of 120mm fans in a push-pull configuration. It comes supplied with a wealth of high-quality fitting equipment, including thermal paste, fan splitters and ‘quiet fan adaptors’, and nicely produced instructions. There’s a robust metal backplate supplied for Intel.

Fitting is easy, with the exception of some confusion over the correct bushings to use: there’s white, beige and black bushing supplied, and it’s the black ones that are used for intel LGA1200 and LGA1155 fitment, but we had to check this with Noctuas online fitting videos as the instructions aren’t clear, mentioning a part number when stating the colour would have been far more helpful. The brackets are robust, and you can fit them horizontally or vertically according to preference. There are no compatibility issues with RAM, or the GPU on an mATX motherboard so it’s versatile, whilst the total height of 158mm means it’ll fit into a wide variety of cases.

Cooling performance is excellent as you’d expect and the fans are barely audible although they run at 1200 RPM, faster than the 140mm fan coolers in this test. This isn’t intrusive despite 120mm fans thanks to the exceptional fan quality. Temperatures are on a par with the larger coolers, sitting at 60C. Noctua suggests using one of the fans to replace the case exhaust, and in most configurations, we’d second that as a great low noise alternative to a supplied case fan. Moving from push-pull to a single fan barely affects temperatures at all. 

Noctua NH-U12A Contents

Any criticism of the U12S is either personal preference or splitting hairs: The instructions could clear up the bushing confusion with a single mention of the correct colour. The colour of the fans is entirely down to preference, but they are somewhat love or hate, and hard to integrate into a more showy build. There are chromax adaptors to cover the heat fin stack, but they’re extra. It also feels a little expensive, largely down to the quality of fans included which are unrivalled.

Ultimately, this cooler is all about performance, and it nails that. If you need a top tier solution with reliability and engineering a priority, and don’t mind the looks, then this is the cooler for you.

Noctua NH-U12ANotes:Rating
Supplied AccessoriesSupplied with instructions, brackets, clips, two AF-A12x25 fans, thermal paste in a tube and a make-shift screwdriver. Low noise adaptors x2 and Noctua badge.****
Ease of fitmentWell made bracketry and excellent instructions make this cooler easy to fit. Only clearing up the correct bushings would improve this score. ****
NoiseVery low noise operation under load thanks to 1200mm fans of exceptional quality.****
Cooling PerformanceTop tier cooling performance that can handle any CPU on the market. For an i9 or Ryzen 9 CPU we’d recommend an NH- D15 though.*****
ValueExpensive, but justified owning to the quality of the parts and design.***
ConclusionA top tier cooler with versatile fitment and great performance. ****

2. Be Quiet! Dark Rock 4

The Bequiet! Dark Rock 4 is a six heat-pipe heatsink with a single 135mm fan. This cooler is supplied with a bar-style retainer and high-quality bracketry, as well as a really high-quality long reach screwdriver that you can use for the rest of the PC build. Assembling the metal backplate and pins for intel applications is fiddly but other than that fitting is straight forwards. The fan does interfere with the first RAM slot for all but the lowest profile RAM, so if you’re planning four sticks you might want to look elsewhere, or else ensure the case has clearance for the fan to be mounted higher. This configuration negatively impacts the clean looks of this cooler.

Be Quiet Dark Rock 4

The Dark Rock 4 is another largely silent cooler with good thermal performance. In our testing fan speed is amongst the lowest at just 800RPM, whilst it allows temperatures to sit a little higher at 70C. Adjusting fan speed allows you to strike the balance that’s right for you. It’s well suited to higher performance AMD CPUs, and it’ll handle Intel’s latest i5 CPUs, and the i7 non-K CPUs too. If you’ll looking at cooling an i9, the 10850K or 11900K for example, we’d recommend something with more cooling power as those CPUs can overwhelm even this cooler. For everything else, it’s recommended as a compatible, well made and good looking cooler with great reliability and performance.

Dark Rock 4Notes:Rating
Supplied AccessoriesSupplied with instructions, brackets, clips, 2 fans, a small amount of thermal paste in a tube and a good quality long reach screwdriver.*****
Ease of fitmentSimple and intuitive fitting mechanism. You may need to fit the cooler after mounting the motherboard if the space in the case is tight.****
NoiseAmongst the quietest coolers on test with low fan noise and 800rpm operation under load.****
Cooling PerformanceSuitable for Intel i5 and i7 CPUs, and Ryzen 5 and 7. Intel i9 and Ryzen 9 should look to the Dark Rock Pro 4. ****
ValueGood value at around $70****
Overall RatingAn excellent, widely compatible and attractive cooler that meets almost any need.****

3. Noctua NH-D15S

Noctua NH-D15S

Straddling the gap from single fan to dual fan coolers, the Noctua NH-D15S is a split heatsink cooler with six heat pipes. It’s supplied with a single 140mm fan. The cold plate is offset to provide more versatile compatibility with GPUs. It fits on an mATX motherboard, unlike the larger NH-D15. There’s also a notch in the radiator fins to allow for higher RAM, although we’d advise checking RAM height for clearance (it should be less than 62mm) before purchase. 

As you’d expect given Noctua’s attention to detail, the bracketry is blacked out on this Chromax version, to match the cooler. Fitting is easy enough though we’d recommend working out whether you’re better off fitting the cooler when the motherboard is inside the case, or outside – this really depends on the access into your case around the cooler once fitted and it’s even more of an issue on the larger dual fan version. 

Noctua NH-D15S Contents

Under test, the NH-D15S produces excellent thermals sitting at about 62C CPU temperature, and as you’d expect, virtually zero fan noise with the 140mm fan at about 850 rpm under load. The NH-D15S an excellent cooler, and usefully addresses some of the compatibility issues of its bigger brother making it a great all-rounder performance cooler for a high-end CPU. 

Noctua NH-D15S Chromax.blackNotes:Rating
Supplied AccessoriesSupplied with instructions, brackets, clips, one fan, thermal paste in a tube and a make-shift screwdriver. Low noise adaptor and Noctua badge.****
Ease of fitmentGood instructions and simple fitting process, but will be complicated by fitting inside a case with restricted access.***
NoiseVery low noise operation even under load.*****
Cooling PerformanceExcellent, capable of cooling all but overclocked i9 CPUs. ****
Value$100 marks this as a premium product***
Overall RatingAn excellent, versatile cooler that solves many of the compatibility issues with the NH-D15 with minimal compromises to performance. ****

4. Be Quiet! Dark Rock Pro 4

The Dark Rock Pro 4 sits at the top of Be Quiet’s product lineup. It uses a split fin stack with a 135mm fan in the centre and a 120mm fan at the front face to drive air right through in a push-pull configuration. The smaller improves compatibility with RAM but you are going to want to carefully check RAM height before ordering this cooler, it does overhang slots and will obscure RGB RAM. It will not interfere with GPU’s on ATX or MATX motherboards. 

Be Quiet Dark Rock Pro 4

The fitting equipment for the Dark Rock Pro 4 is high quality, and the fitting procedure is well explained but tricky. The included screwdriver is absolutely necessary to reach the screw positions through the facing plate. Securing the fan retention clips can be tricky if the case doesn’t allow good access, whilst if you choose to fit the cooler prior to fitting the motherboard, you can run into problems screwing down the upper motherboard screw or fitting power and fan plugs. Plan your build process carefully around this cooler. 

Once assembled the cooler gives one of the cleanest and most impressive appearances of any air cooler, and thermal and noise performance is top-notch. This cooler will handle anything short of overclocking the most demanding consumer CPUs, for which you’ll want a water cooler with a large radiator, or a custom loop anyway. Thermal performance matches all but the Noctua NHD15 in our test, whilst fan speeds remain low at 850RPM. It takes our recommendation due to the combination of performance, compatibility and low noise.

Dark Rock 4 ProNotes:Rating
Supplied AccessoriesSupplied with instructions, brackets, clips, 2 fans, a small amount of thermal paste in a tube and a good quality long reach screwdriver.*****
Ease of fitmentTricky fitment owing to enclosed dual fan design and the need to assemble the PC In the right order. ***
NoiseVery low noise operation thanks to dual fans and low fan speeds.****
Cooling PerformanceCapable of cooling all but a heavily overclocked intel i9 CPU*****
ValueGood value at $90****
Overall RatingAn excellent one-stop solution to cool the most demanding CPUs available. ****

5. Noctua NH-D15

Noctua NH-D15 Box

The largest air cooler in this test is the Noctua NHD-15. This is a split heat stack cooler but despite only one letter difference in the name from the NH-D15S, there are some considerable physical differences. The cold plate is not offset, meaning this cooler is only compatible with ATX motherboards – it obscures the top slot in an mATX motherboard making it impossible to fit a GPU. It’s supplied with 2 fans of equal 140mm size, so the front fan will interfere with RAM unless mounted higher, or at the rear of the cooler not the front. Fitting is straight forwards but careful planning needs to go into order of operations: You’ll need to fit RAM before the cooler itself, and ensure that you plug in motherboard plugs before fitting the cooler. Access to do up the fan clips can be hard too. You’ll need a large case and some serious planning to fit this cooler into your build. 

Once fitted, this cooler excels in performance testing: It’s silent and powerful. It kept temperatures the lowest of any cooler on the test, at 58C, with fan speeds matching the other high-performance coolers at 850rpm.

The downsides are really the cost, and the compatibility ‘cascade’ you need to consider to incorporate this cooler into your PC. The motherboard type, case size and ram selection all hinge on this Cooler. If you were planning a full-scale ATX build anyway that’s not a compromise, but it does preclude more tightly packaged builds. The looks are down to personal taste, but if you prefer a less distinctive colour scheme there’s also a ‘Chromax’ black version for $10 more. Noctua also supplies Chromax colour panels to adjust the scheme to match other aesthetics – though these do add considerably to the cost. 

Noctua NH-D15 Contents

This is undoubtedly the best performing tower cooler in this test, but you will need to plan your build carefully to incorporate it. It’s the go-to solution where reliability and performance trump other considerations, with redundancy provided by the dual fans. The other coolers, like the NHD15S or the Dark Rock Pro 4 come very close to the performance but are much more user friendly to integrate into a build and offer better value too.

Noctua NH-D15Notes:Rating
Supplied AccessoriesSupplied with instructions, brackets, clips, two AF15 fan, thermal paste in a tube and a make-shift screwdriver. Low noise adaptors x2 and Noctua badge.****
Ease of fitmentGood brackets but the fitting process is fiddly owing to the reduced access.***
NoiseThe lowest noise cooler on test, with two 140mm fans barely audible at full load.*****
Cooling PerformanceCapable of cooling any consumer CPU. *****
ValueAn expensive cooler at a premium price point.***
Overall RatingThis cooler is undoubtedly the best performing in the test, but comes at the cost of compatibility compromises.****

Performance Testing

To test these coolers we mounted them to a test system comprising of an Intel i5-11500. This CPU consumes 110W at full load with power limits, giving sufficient heat output to examine the performance of these coolers. It’s equivalent to a Ryzen 9 5900X.

Air CPU Cooler Test Cinebench R23
Tower Cooler Test CPU Package Temperatures vs Time

We can see that the Dark Rock 4 differs most from the other high-end tower coolers on test; It has the lowest fan speed at 750RPM and allows the CPU to reach the highest temperatures, but still delivers a very reasonable 70C overall temperature.

The Noctua NH-U12A is the only fan in the test with just 120mm fans, and the higher fan speed of 1200 rpm is the result of this. The cooling performance is still exceptional though and the very high-quality fans stay effectively silent.

The Noctua NH-D15, NH-D15S and the Bequiet Dark Rock Pro 4 are hard to distinguish – all deliver temperatures around 60°C and fan speeds at about 800RPM. All have ample headroom to tune temperatures or fan noise to your preference even with demanding CPUs. 

Conclusion: Take your pick on looks, value or compatibility.

Best Air CPU Coolers

Each of these high-end air coolers has much to recommend. The right choice for your build really relies on your preferences. The Noctua NH-D15S is impressive in performance and noise and is much more forgiving of RAM and Motherboard form factor than its larger sibling. Personally, we prefer the Dark Rock Pro 4’s combination of looks and thoughtful design, meaning it requires fewer compromises overall and looks fantastic in most systems without spending more on aesthetic accessories. 

Meanwhile, the Noctua NH-U12A and Dark Rock 4 absolutely have a place in build with slightly less demanding CPUs or more size constraints, you don’t sacrifice anything in noise or performance in opting for one of these CPU coolers. 

Lastly, the Noctua NH-D15 will find its home in a full-scale ATX build where high-performance CPUs need to work at optimal temperatures with minimal noise. If you’re using a large case anyway, this cooler brings AIO levels of performance without the complexity of adding an all in one water loop to your PC: It’s a great choice if you value low noise above all else.

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