We hope this article helped you learn more not only about the particular coolers we reviewed, but also about CPU cooling more in general. First things first, if you’re new to PC building or modification, you can rest assured that the stock Intel cooler will properly cool your CPU under all stock conditions. While it did “fail” the Intel Burn Test, IBT is an extreme stress test that goes beyond the load that any typical application would impose. 

It's also important to note that Intel processors do not “break” when the temperature hits 100C, but rather throttle their clockspeed and voltage to reduce core temperatures. You’d have to really push an Intel processor for a very long time before it was damaged due to heat. That being said, we’d advise that you monitor your CPU’s temperature upon first assembling or modifying a PC to ensure that the heatsink is properly attached. As we demonstrated, it’s possible to attach an Intel cooler without it being fully locked in, and under these circumstances, processor damage is more likely.


The smallest of the aftermarket coolers we tested was the Noctua NH-L9x65. We’ve done a separate in-depth review of this cooler, and in short, it really comes into its own when used with the low-noise adapter included with the cooler (and all Noctua coolers, as a matter of fact). In this round-up, we chose to run it at full speed to give it a better chance against the bigger coolers, but in all honesty, it’s a different product for a different application. Downdraft coolers are naturally at a disadvantage versus tower coolers, and the small proportions of the NH-L9x65 mean it’s never going to win in a head-to-head battle with its bigger cousins. But the fact that it will fit in every micro ATX case, and nearly every mini-ITX case, makes it one of the very few coolers we can recommend for these applications without hesitation. Many downdraft coolers are not only much taller, but also have a much larger footprint, making them a risky proposition in an ITX system. To see how close we came to failure in using a big downdraft cooler in an ITX system, see our Project ITX article. Note that the NH-L9x65 isn't actually Noctua's smallest cooler; that would be the NH-L9i, which is the cooler you'd want to use for ultra-slim systems that can't accommodate the 65mm height of the NH-L9x65.

Next on our list in terms of size is the Noctua NH-U12S. If there were one aftermarket cooler that we would have no hesitation recommending to every PC enthusiast, the NH-U12S would be it. Built to Noctua’s exacting specifications, the NH-U12S is nearly silent at idle and still relatively quiet when pushed to the max, while being by far the easiest tower cooler we’ve ever had the pleasure of installing. At just 158mm tall, it will also fit easily into most mid-sized ATX cases. Plus, the NH-U12S works extremely well, better in fact than every other 120mm cooler we’ve tried in the past. It even includes a second pair of fan clips to allow you to attach another NF-F12 fan, turning the NH-U12S into a true ultra-high-end cooler. Now, there’s just one fly in the ointment keeping the NH-U12S from being flat-out perfect, and that’s price. It’s not only more expensive than every other 120mm-based cooler, it’s also more than many 140mm-based models. It even approaches the price of the Noctua NH-U14S, which is essentially the 140mm version of the U12S. That being said, the elegance, broad case and motherboard compability, and best-in-class fan of the NH-U12S make it worth paying for, as long as you don’t need the absolute highest-capacity cooler out of the box.


Next up is the impressive Thermalright Macho Rev. B. Thermalright keeps a low profile in the PC building community, but it’s been busy churning out absolutely killer CPU coolers for a long time, and the Macho Rev. B’s combination of stellar performance, impressive low-noise, low-RPM operation, and competitive price make it a true winner. It’s actually the cooler we’d personally choose to run in our system among the ones we tested, based in part on its eye-pleasing style. That being said, we weren’t huge fans, no pun intended, of the slightly raspy tone given off by its 140mm fan, even at low speeds. In addition, the installation process was fairly challenging, due to the cooler’s massive bulk and the slightly awkward bracket and fan clip design. Still, in terms of bang-for-the-buck, you simply won’t find a better cooler, although the Macho's cousin the Thermalright True Spirit 140 Rev. A might offer a better overall package when factoring in ease of installation and system compability.


Moving on to the Noctua NH-D15, our feeling is that it’s a very niche product. It can compete with 240mm liquid coolers, and that’s probably the target Noctua was aiming for when it designed the NH-D15. Noctua doesn’t make liquid coolers, so going with reallybig air was its only option for keeping up. But here’s our take: Noctua’s operating a bit out of its comfort zone with the NH-D15. When equipped with dual-fans, which spin up to a very high 1500RPM, the D15 was simply being run ragged, abandoning the quiet, composed behavior that Noctua is known for (note, however, that as with all Noctua products, low-voltage adapters are supplied in the box, which would limit the maximum speed to 1200RPM). It was also somewhat difficult to install, and proved to be incompatible with tall RAM heatsinks, a major faux pas for a company that prides itself on broad compatibility. On the flipside, we were very impressed by the NH-D15 when using just its single mid-mounted fan (at least when mounted horizontally), and in fact this would be our preferred setup if we were to choose one. But Noctua only sells the NH-D15 with two fans, which pushes the price up towards $100, and that, to be frank, is just too high for an air cooler. Big air has its place, but we don’t think it should be forced to compete with high-end 240mm liquid coolers. Each has its advantages, and one major advantage of air cooling is simplicity, which typically also means lower cost. [Update: Note that after we published this article, Noctua reached out to let us know that the single-fan NH-D15S will soon be released for $79.99!]


Finally, we have the Corsair Hydro H100i. Among the most popular 240mm liquid coolers ever released, it serves as a great demonstration of the power and the promise of liquid cooling. By separating the heatsink from the radiator, the exhaust can be moved to the edge of the case environment, while in the process providing additional case cooling. Versus air-cooled towers, liquid coolers are also less likely to interfere with other system components and won’t cause damage during transit, as most of the weight is bolted directly to the case, rather than the motherboard.

We predict that one day, all CPU coolers will be liquid coolers, because they just make so much sense. In the here and now, however, there’s one big problem: pump noise. Moving heat (via a liquid medium) from one location to another requires a lot of energy, and that means noise. Unfortunately, with very rare exceptions, today’s liquid coolers do not use variable-speed pumps, and so that heavy liquid is being pushed around all the time, even when cooling requirements are minimal. Indeed, the H100i's noise level is deeply disappointing at idle, but strap it to an overclocked system, select the software-controlled “Quiet” mode in CorsairLink, max your CPU out in your favorite application, and experience the future. Able to out-compete even the most powerful dual-fan 140mm air cooler on the market, despite producing noise levels below most 120mm single-fan air coolers, the H100i was Corsair’s first shot at a dream cooler, and the new H100i GTX is no doubt even closer to the dream fulfilled.

So, to wrap up, here’s what we hope you gleaned from our in-depth investigation of CPU cooling:

  1. When using a stock-clocked processor and typical computing applications, the stock Intel cooler is always sufficient, and relatively quiet too.
  2. To gain some overclocking headroom, a good 120mm tower cooler is your next step up, with 92mm or 120mm downdraft coolers a fallback in slim systems. Be wary of coolers that come in under $25 – most will barely outperform the Intel cooler, and will likely be louder as well.
  3. For the perfect combination of overclocking support and ultra-low noise, there’s no better option than a low-RPM 140mm cooler. Despite costing just a bit more than 120mm coolers, these models really operate in a different league. But keep in mind that installation will always be a bit more difficult, their width means the first motherboard expansion slot is often blocked (which will spell doom for micro ATX systems), and at over 160mm tall, they will not fit in narrow ATX cases. And don't try to get around space issues by orienting a 140mm cooler to exhaust towards the top of the case. The optimal installation method is always to have the cooler blow towards the back of the case. If that won't work, use a 120mm cooler.
  4. Finally, if you’re looking for the ultimate in high-voltage overclocking, with noise levels being only a secondary concern, you must go to dual-fan liquid cooling. We didn’t test a single-fan model, but to be honest, they aren’t worth bothering with unless your case can’t accommodate a double-wide radiator. The 240mm models (as well as the even larger 280mm and 360mm models) are where it’s at in terms of liquid cooling. They’re often just $10-20 than comparable single-fan models, despite having twice the cooling capacity. Another advantage of liquid coolers is that they aren't affected by hot-running video cards. In fact, it's the only type of cooler we recommend for use in Crossfire and SLI gaming systems utilizing open-air rather than blower-style video card cooling.

One last tip: running any CPU cooler at maximum RPM all the time is downright silly, and unfortunately, many CPU cooler reviews only test this scenario, or else show fixed, arbitrary RPM settings. Using default motherboard PWM control is the easiest way to set up your fans, but in case this doesn't turn out to be as optimal as you might wish, loading up your motherboard’s software controls is always a great option, and one we highly recommend to dial in just the right balance of noise and performance. A screenshot below shows the fan controls provided by our Asrock test board. They can be freely adjusted by the user to allow for ultra-low RPM operations at low temperatures, with higher RPMs when necessary. In this example, we set the fan to max out at 80°C, but you can choose any target you feel comfortable with.

Fan Tuning

All told, we put over 40 hours into writing this article, which included product installation, photography, benchmarking, charting, and the drafting of our analysis. As with our past in-depth guides, our goal was to provide our readers with a comprehensive but easy-to-understand analysis of a complex topic. We hope you’ve enjoyed what we came up with, and more importantly, that you’ve learned something new to apply the next time you're ready to build or modify a PC.

Update: After we originally published this article, we put together a CPU Cooler Buyer's Guide, which is updated on a regular basis. If you're looking for our current top picks at every pricepoint, you'll definitely want to check it out!

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