The Arctic Cooling Liquid Freezer II 240 & 420 AIO Coolers Review: Big and Effective

Arctic Cooling is a company originating from Switzerland and has risen to prominence for their advanced cooling solutions. The company was founded back in 2001 and offered some of the best thermal compounds available at the time. Today, cooling products remain the core focus of the company, but they also offer a few other products as well, such as advanced monitor mounts and audio peripherals.

Over the past several months, Arctic Cooling has been picking up from a dry spell in top-tier CPU coolers, having gone a few years since their previous release. Last year, the company introduced the first parts in their their Liquid Freezer II all-in-one liquid cooling series, expanding the range as the months went by. A few weeks ago the company announced the release of the massive Liquid Freezer II 420, triple-fan AIO cooler that holds not three 120mm fans – as is usually the case with triple-fan coolers – but three even larger 140 mm fans. Arctic Cooling set out to cover the market from bottom to top with their Liquid Freezer II coolers, and the introduction of a 420mm design has certainly cemented that status.

In this review, we are taking a look at a couple of Arctic Cooling’s Liquid Freezer II coolers. We’re of course diving into the behemoth 420 AIO cooler, but also the much more sensible 240mm version of the cooler. How well does such a large cooler perform with regards to thermals and noise? And just how much better does that make the super-sized cooler over the more normal, widely compatible version of the same cooler? Let’s find out.

 

Arctic Cooling supplies the Liquid Freezer II series in relatively simple but sturdy recyclable cardboard boxes. The artwork on the box is based on a schematic of the cooler itself, with plenty of information regarding the cooler on the backside of the box. Inside the box, we found the coolers and their parts well protected by cardboard inserts and nylon bags.

The bundle supplied with the Liquid Freezer II coolers is the same regardless of the cooler’s size. Unfortunately, the MX-4 thermal compound that the company advertises to be included is a single dose, not a whole tube. The rest of the bundle consists of the necessary mounting hardware, all in black color. There is no paper manual but there is a card with a QR code, which in turn leads to an downloadable manual.

As expected, the main difference between the 240 and 420 versions of the Freezer II is the size of their radiators and fans. Other than that, the two all-in-one (AIO) liquid coolers are identical, using the same main block and tubing. The core design of the coolers is the typical AIO configuration of a single radiator, two hoses, and a block that combines the CPU contact plate and a miniature liquid pump. One major divergence compared to competitive products is that the fans are already installed onto the radiators and everything is pre-wired, with the whole assembly powered by a single 4-pin connector coming out of the block. And while pre-assembly isn’t strictly necessary for an AIO cooler, anyone who has assembled a cooler can probably appreciate the time saved by not having to line up screws, power cable orientations, etc. Furthermore, recognizing that some users may want to reconfigure and reassemble the cooler anyhow, the company’s designers added regular fan connectors onto the radiator, meaning that one can seamlessly replace the fans if needed.

Arctic Cooling is using high-density rubber for minimal long-term evaporation that should last for the lifetime of the cooler, with no filling/service ports to be found. The hoses are protected by a nylon sleeve with a circular dual silver thread design. The nylon sleeve also hides the cable that powers the fans. Chromed metal press fittings are used to secure the tubing on both ends.

The radiators of the Arctic Cooling Freezer II AIO coolers are dual-pass cross-flow designs with tiny fins soldered on thin oblong tubes, yet they are not based on the same exact design that most AIO coolers use. Regardless of variant, all of Arctic Cooling’s Freezer II radiators are rectangular constructs that are significantly thicker than standard designs, measuring 38 mm thick without the fans and nearly 65 mm with the stock fans attached. The 420 version of the Freezer II also sports the largest radiator we have seen used by an AIO cooler to this date and comes with three 140 mm fans installed. It is not the longest, as there were a few 4×120mm (480) radiators circulating the market over the past few years but, even compared to these, it has significantly more heat exchange area. Consequently, case compatibility may be a challenge for this behemoth.

 

 

The main block assembly of the Freezer II is short and relatively simple, with one major difference discerning it from most competitive products – there is a small 40 mm fan attached to it. This fan has practically nothing to do with the cooling of the CPU itself but is meant to provide some airflow to the motherboard’s power circuitry that would normally be cooled by the air cooler’s airflow. Other than that, the assembly includes the copper contact plate and the mini pump.

The square copper contact plate is not machined down to a complete mirror finish but is very smooth. It is large enough for most commercial processors but will not cover a ThreadRipper processor, for which the Freezer II coolers have no stock support for out of the box.

Although the testing of a cooler appears to be a simple task, that could not be much further from the truth. Proper thermal testing cannot be performed with a cooler mounted on a single chip, for multiple reasons. Some of these reasons include the instability of the thermal load and the inability to fully control and or monitor it, as well as the inaccuracy of the chip-integrated sensors. It is also impossible to compare results taken on different chips, let alone entirely different systems, which is a great problem when testing computer coolers, as the hardware changes every several months. Finally, testing a cooler on a typical system prevents the tester from assessing the most vital characteristic of a cooler, its absolute thermal resistance.

The absolute thermal resistance defines the absolute performance of a heatsink by indicating the temperature rise per unit of power, in our case in degrees Celsius per Watt (°C/W). In layman’s terms, if the thermal resistance of a heatsink is known, the user can assess the highest possible temperature rise of a chip over ambient by simply multiplying the maximum thermal design power (TDP) rating of the chip with it. Extracting the absolute thermal resistance of a cooler however is no simple task, as the load has to be perfectly even, steady and variable, as the thermal resistance also varies depending on the magnitude of the thermal load. Therefore, even if it would be possible to assess the thermal resistance of a cooler while it is mounted on a working chip, it would not suffice, as a large change of the thermal load can yield much different results.

Appropriate thermal testing requires the creation of a proper testing station and the use of laboratory-grade equipment. Therefore, we created a thermal testing platform with a fully controllable thermal energy source that may be used to test any kind of cooler, regardless of its design and or compatibility. The thermal cartridge inside the core of our testing station can have its power adjusted between 60 W and 340 W, in 2 W increments (and it never throttles). Furthermore, monitoring and logging of the testing process via software minimizes the possibility of human errors during testing. A multifunction data acquisition module (DAQ) is responsible for the automatic or the manual control of the testing equipment, the acquisition of the ambient and the in-core temperatures via PT100 sensors, the logging of the test results and the mathematical extraction of performance figures.

Finally, as noise measurements are a bit tricky, their measurement is being performed manually. Fans can have significant variations in speed from their rated values, thus their actual speed during the thermal testing is being recorded via a laser tachometer. The fans (and pumps, when applicable) are being powered via an adjustable, fanless desktop DC power supply and noise measurements are being taken 1 meter away from the cooler, in a straight line ahead from its fan engine. At this point we should also note that the Decibel scale is logarithmic, which means that roughly every 3 dB(A) the sound pressure doubles. Therefore, the difference of sound pressure between 30 dB(A) and 60 dB(A) is not “twice as much” but nearly a thousand times greater. The table below should help you cross-reference our test results with real-life situations.

The noise floor of our recording equipment is 30.2-30.4 dB(A), which represents a medium-sized room without any active noise sources. All of our acoustic testing takes place during night hours, minimizing the possibility of external disruptions.

<35dB(A) Virtually inaudible
35-38dB(A) Very quiet (whisper-slight humming)
38-40dB(A) Quiet (relatively comfortable – humming)
40-44dB(A) Normal (humming noise, above comfortable for a large % of users)
44-47dB(A)* Loud* (strong aerodynamic noise)
47-50dB(A) Very loud (strong whining noise)
50-54dB(A) Extremely loud (painfully distracting for the vast majority of users)
>54dB(A) Intolerable for home/office use, special applications only.

*noise levels above this are not suggested for daily use

Our maximum speed testing is performed with both the fans and the pump of the kit powered via a 12V DC source. This input voltage should have the pump and fans matching the speed ratings of the manufacturer. Arctic Cooling rates the 120 mm fans of the Liquid Freezer II 240 at 1800 RPM and the 140 mm fans of the Liquid Freezer II 420 at 1700 RPM. According to our tachometer, the fans were rotating at 1820 RPM and 1610 RPM respectively, with the 120 mm fans landing very close to their specification but the 140 mm fans were considerably slower than expected, yet still within a reasonable ±10% tolerance.

Average Thermal Resistance

Core Temperature, Constant Thermal Load (Max Fan Speed)

At first glance, the average thermal performance charts reveal that the Liquid Freezer II 420 is significantly outperforming any AIO cooler that we have tested to this date. With an average thermal resistance of 0.0576 °C/W, the Liquid Freezer II 420 is exceeded only by a high-end, open loop cooling kit (the Alphacool), and even then it’s rather close. One must not forget that the radiator of the Liquid Freezer II 420 also is the largest that we have ever tested, with the design relying on the massive thermal exchange area for its exceptional thermal performance. Still, the flow of the minipump inside the block assembly holds the Liquid Freezer II 420 back, with the advantage of Alphacool’s much more powerful pump being greatly apparent at low loads.

The sound pressure level of the cooler is at 43.8 dB(A), which is on the high side for comfortable use, but to be expected from a cooler using three high speed 140 mm fans.

Fan Speed (12 Volts)

Noise level

The 240 version of the cooler also performs very well, providing strong competition to equally-sized coolers. The average thermal resistance of the Liquid Freezer II 240 at full fan speeds is 0.0745 °C/W, placing it a tiny bit ahead of most of its direct competitors in terms of thermal performance. However, the sound pressure level of 42 dB(A) is higher than the figures we got from competitive products, with the 40 mm fan on the block mostly responsible for the increased noise output.

Using a PWM voltage regulator, we reduced the speed of the fans manually down to half their rated speed, which is 900 RPM. The pump was also connected to the same power source, functioning properly at this low-speed setting.

Average Thermal Resistance

Core Temperature, Constant Thermal Load (Low Fan Speed)

The Liquid Freezer II 240 seems to be doing great in this test, with an average thermal resistance of 0.0896 °C/W, surpassing nearly all equally sized AIO coolers. The catch is that it also is significantly louder than its direct competition as well. The emitting sound pressure of 36.7 dB(A) is not high enough to be considered loud, yet the difference over competitive products is significant and discernible.

Fan Speed (7 Volts)

Noise level

The massive proportions of the Liquid Freezer II 420 give the cooler a great performance advantage even when its fans and pump are at half speed. With an average thermal resistance is 0.0783 °C/W, the Liquid Freezer II 420 thermally outperforms everything that we have ever tested to this date. The sound pressure of 37.9 dB(A) is on the high side though, as expected from three 140 mm fans plus a small 40 mm fan on the main block.

During our thermal resistance vs. sound pressure level test, we maintain a steady 100W thermal load and assess the overall performance of the coolers by taking multiple temperature and sound pressure level readings within the operating range of the stock cooling fans. The result is a graph that depicts the absolute thermal resistance of the cooler in comparison to the noise generated. For both the sound pressure level and absolute thermal resistance readings, lower figures are better.

In this graph, we can discern how Arctic Cooling’s liquid coolers rank against the competition at a reasonable power level. We see that the Liquid Freezer II 240 can reach thermal resistance values slightly lower than competitive coolers but can be a bit louder than other designs. Much of that noise is coming from the additional 40 mm fan on the block but the significant backpressure of the thick radiator also is a bit to blame. The thermal performance of the Liquid Freezer II 420 is better than most of the competition but its performance edge is not that great under these operating conditions, as the massive cooler practically requires an equally massive load to reach its optimal operating conditions.

Arctic Cooling designed the Liquid Freezer II series of all-in-one coolers for users who value subtle designs and seek a good price-to-performance ratio. The series currently consists of five coolers, ranging from a small single 120 mm version to the massive three 140 mm fans version that we reviewed today. All share the same main block and tubing, making the choice of radiator more of a compatibility matter than anything else.

Although they look very simple at first glance, the Liquid Freezer II coolers actually are niftily designed. They combine quality and elegance in an ingenious way rather than relying on colorful lighting to draw attention. The designer’s idea to incorporate the wiring of the fans into the cooler has several advantages, including quicker installation and a very clean appearance once installed. Our only worry lies with using the triple-fan models with low-end motherboards, as it’s possible that the power circuitry of the motherboard may be overloaded by the entirety of the cooler’s power needs. Then again, there probably aren’t too many builders and PC enthusiasts installing such a massive liquid cooler on a low-end motherboard to begin with.

In terms of performance, the Liquid Freezer II produces very good results. Their thermal performance seems to be excellent, with the cooler that we have tested outperforming similarly-sized competitors. Most of that advantage comes from the radiators, which do offer better heat exchange rates but, on the other hand, their thickness absolutely needs to be taken into account when determining if the cooler is compatible with a given case/system. Meanwhile, the acoustics performance of the Liquid Freezer II coolers is somewhat worse compared to that of similar offerings, with the small 40 mm fan on the main block being mostly to blame for these results. Nevertheless, the coolers are not actually loud or intrusive and most users would probably welcome the additional cooling for the motherboard’s vital power components.

Arctic Cooling is a company that typically designs practical, ‘no-frills’ products, aiming to perform reliably and retail at a reasonable cost. The Liquid Freezer II AIO coolers are no exception, as they are sporting a subtle design and offer excellent overall performance at a very reasonable price tag: the 240 model sells for just under $100, and even the mammoth 420 model is only $160 – at least if you can find it in stock.

Ultimately, If you are seeking to purchase a high-performance cooler and do not care about RGB lighting or other aesthetic features, the Liquid Freezer II coolers are equally capable products that retail at a significantly lower retail price than most of the competition and should definitely be on your shortlist for consideration.