Maximum Fan Speed

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.

Low Fan Speed

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.

Thermal Resistance VS Sound Pressure Level

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.

Testing Methodology Final Words & Conclusion


View All Comments

  • whatthe123 - Friday, January 15, 2021 - link

    It's really more about the pump than the thickness. Other non-asetek pump solutions like the new lian li and EK perform basically the same as the liquid freezer 2. you'd need a really large die and a lot of power pulled through it before the rad became the real differentiating factor. Reply
  • Tunnah - Friday, January 15, 2021 - link

    What would be an interesting test is to see the temperatures with the fans running minimum speeds. I prefer quiet over temps so my 3700X/NH-D14 with 2 fans run at 300RPM-600RPM to keep it around 60c, and only spin up if it goes up to 80c. Been thinking about getting a beefier cooler so I can keep it cooler at the same sort of fan speeds. Reply
  • lorribot - Friday, January 15, 2021 - link

    Whilst maximum cooling potential is useful for those that can configure the system in a certain way (hide in a cupboard) it is not practical for most people, what would really good is temps and fan speed at a given noise level, such as 30db, 32db and 35db, then, given your personal preference/tolerance you would then buy based on performance at your prefered sound threshold and set fans to an appropriate speed. Using 7 volts an 12 volts is pretty pointless.
    I have never seen this sort of testing in any review.
  • Galcobar - Saturday, January 16, 2021 - link

    Gamers Nexus includes noise-normalized testing in its cooler and case reviews, and has covered most of the Liquid II line. Artic is at or near the top of the GN cheers for thermal/noise efficiency, despite the relatively lower MSRP. The fans of course play a large role in this, which is in line with their near-Noctua results in Optimum Tech's fan roundup. Reply
  • bug77 - Friday, January 15, 2021 - link

    I've always built my own system, but never understood the appeal of these. They're not quieter than air cooling and they come with a bunch of problems on their own. Reply
  • Spunjji - Monday, January 18, 2021 - link

    They can be quieter than air cooling if you're doing some serious overclocking, not to mention you then avoid having the 1Kg+ of weight you'd need hanging off your motherboard to get similar cooling potential with air alone. It can also allow you to remove the heat directly from the case with the right case design (venting from the top).

    I'd agree that it's overkill for the majority of users, though. The last time I used AIO coolers were with adaptors for GPUs, which made way more sense - I could get a combined cooling and noise level combination that was simply impossible with air cooling, but cheaper than a custom loop.
  • Solidstate89 - Monday, January 18, 2021 - link

    I don't know why you'd make such a blatantly false statement but these AIO coolers are almost always quieter than an air cooler. Reply
  • Dug - Monday, January 18, 2021 - link

    That is not true if you look at any normalized sound testing. In almost all cases a good air cooler will be quieter because you don't have pump noise, and you have less restricted air flow. Noise is going to come from two things, fans and pump. While pump noise may not be loud, it can be annoying. Like a mosquito isn't loud, but killing it makes all the difference in the world. Reply
  • cellarnoise - Friday, January 15, 2021 - link

    1st post on a product review since 1997 ish? I can't remember my original user name or password, but keep coming back here a long time. I'm preparing for a 5950x if I can ever find one, so I bought this 420. Love it. Running in a slightly modified Fractal s2 case that I modified to move the 420 closer to the glass side of case away from the motherboard so my mid-height RAM could fit without touching the AIO. Love it! Running on 1700x at 3.8 BOINC load 24/7 it is much quieter as fans sit under 500 rpm for 130w load. At anything but idle this runs much quieter than the single tower Noctua NH-U14s that I had on this before and I have another equivalent on an 1950x sitting in a solid sided Fractal R5. I love the silence and hope it does well on the 5950x at 250W or so. Reply
  • Dorkaman - Saturday, January 16, 2021 - link

    Hi are the radiator copper or aluminum? Custom looos are usually copper and have considerably better heat sink. Reply

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