Testing Results, Maximum Fan Speed

To begin with, we are having a look at the Be Quiet! Pure Rock 2 FX with its stock 120 mm fan running at its maximum speed.

Average Thermal Resistance

Core Temperature, Constant Thermal Load (Max Fan Speed)

Overall, the performance figures we received from the Pure Rock 2 FX were not far from other similarly-sized products. With an average thermal resistance of 0.1436 °C/W, the Pure Rock 2 FX lands very close to most single-array 120 mm fan tower coolers, such as the Noctua U12A and the Cooler Master EVO 212. It has a relatively steady thermal profile, with the thermal resistance reaching its optimum value with a load of exactly 150 Watts, the design power of this cooler.

Fan Speed (12 Volts)

Be Quiet!’s main focus is quiet operation, and the Light Wings fan does a fairly good job at it. Although the 37.1 dB(A) that we record with the fan running at its maximum speed is definitely not absolutely quiet, it is a very low figure for a fan running at 2000 RPM. The Light Wings fan is audible at maximum speed but the noise pressure level ought to be tolerable for the vast majority of users, even in a very quiet environment.

Noise level

Testing Results, Low Fan Speed

In this test we are switching things up a bit, taking a look at the cooler’s performance with the Light Wings fan taken down to half speed.

Average Thermal Resistance

Core Temperature, Constant Thermal Load (Low Fan Speed)

The reduction of the fan’s speed to 1000 RPM naturally has a negative impact on the thermal performance of the Pure Rock 2 FX cooler, yet that impact is lesser than we anticipated. The average thermal resistance of 0.1812 °C/W is now better than that of most similarly sized CPU coolers, with only the dual fan Noctua NH-U12A and NH-U12S + NA-FK1 coolers managing to outperform it. What gives the Pure Rock 2 FX this performance edge is the speed of the Light Wings fan, which is higher than most other coolers in this test.

Fan Speed

Reducing the speed of the Light Wings 120 mm fan down to 1000 RPM makes the Pure Rock 2 FX cooler practically inaudible. With a sound pressure reading of 32.3 dB(A) at one meter, it should be nearly impossible to notice the cooler unless you're in a dead-silent room.

Noise level

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 temperatures 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.

This chart reveals the standing of the Pure Rock 2 FX cooler against its direct competition. It delivers about the same thermal performance as the Noctua NH-U12S and the SilverStone Argon AR07, yet at either a louder or a quieter noise level respectively. Other similarly sized coolers seem to have lower thermal performance over the same noise levels.

Testing Methodology Final Words & Conclusion
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  • plonk420 - Tuesday, August 8, 2023 - link

    love seeing my U14S on here as well as D15 in comparison. however, my U14S has really made me prefer the noise profile of 140mm fans. also, any chance of reviewing any Scythe coolers?
  • mode_13h - Tuesday, August 8, 2023 - link

    I think Scythe has fallen behind, over the past decade or so. Not that I would mind more cooler reviews and more data on the subject.
  • A5 - Tuesday, August 8, 2023 - link

    Their latest stuff (Fuma 2/3, etc) are at least competitive.
  • IlllI - Saturday, September 2, 2023 - link

    naw, the Fuma 2 is a beast
  • A5 - Tuesday, August 8, 2023 - link

    Yeah the U14S is a great cooler. Would love to see some of the new Thermalright products too.
  • andychow - Tuesday, August 8, 2023 - link

    Once you go Noctua, you don't go back to regular fans or coolers. They are just better, all around. And not in a flashy way. I've had Noctua fans running 24/7 since 2010, and they are still working, still silent.
  • Josh Mason - Wednesday, August 9, 2023 - link

    Agree. I got a Noctua that year and it was the best buy ever.
  • Jorgp2 - Wednesday, August 9, 2023 - link

    Conversely I've had consistent issues with my noctuas.

    PWM just stops working if the cable isn't just right
  • Samus - Thursday, August 10, 2023 - link

    I've had two air coolers in the last 15 years. They are both Noctua's, I still have them, and they are on modern platforms because Noctua sent out a kit to adapt my Socket 1366 cooler to Socket 1151, and recently sent the socket 1700 kit for my old D15. Free both times, no proof of purchase required (even though I had it.)

    Then there are their fans. The only fans I've ever owned that last a long time. I love Silverstone but the fans (especially the 180mm) has bearing issues and once the shaft completely separated from the fan assembly on my FT01. Even those cheap Noctua redux fans have worked well in cheaper systems I've put together like my IP CAM DVR in the garage and the kids' PC.

    Competition is great but I don't really know what it would take to get me to buy another brand of air cooler or fan.
  • escksu - Friday, August 11, 2023 - link

    Perhaps you have yet to seen brands like nidec, sanyo and delta....

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