When liquid cooling became a trend in the 90’s, many companies were founded focused on the design and supply of PC-specific liquid cooling systems. One of these companies was Alphacool, a German manufacturer that diversified into producing liquid cooling systems for industrial and medical applications as well.

Introduction

Perhaps the biggest issue of liquid cooling is complexity, requiring quite a bit of extra effort and attention from the user. For custom loops this was certainly true, even when complete kits were supplied by most manufacturers, as the installation alone is much more complex than that of a simple air cooler. The relative safety and simplicity of all-in-one (AIO) liquid cooling systems does lure those who want a liquid-based cooler with the installation straightforwardness of an air-based cooler. However, AIO solutions are relatively inflexible, and some hardly perform better than high end air-based solutions.

In this review we are having a look at Alphacool’s latest product, the Eisbaer. The Eisbaer, which stands for “polar bear” in German, is a modular AIO liquid cooler that Alphacool designed for those that wish to combine performance and simplicity with future upgrades and flexibility. Alphacool has designed four versions of the Eisbaer that all share the same block/pump assembly but have different radiators and fans. The Eisbaer 120, 240 and 360 come with one, two and three 120 mm fans respectively, while the Eisbaer 280 comes with two 140 mm fans. For the means of this review, Alphacool supplied us with the Eisbaer 240, the dual 120 mm fan version. Although the concept of modular AIO liquid coolers is not new, Alphacool’s liquid cooling parts have had a good reputation, leaving us curious about how their first AIO liquid cooler will perform.

Packaging & Bundle

Alphacool supplies the Eisbaer in a dark cardboard box with relatively simple artwork printed on it. It is very sturdy and the cooler is protected inside a cardboard shell and covered in nylon bags, providing more than enough protection during transport.

The bundle accompanying the Eisbaer 240 is almost typical and limited to the necessary mounting hardware, two “Eiswind” 120 mm fans, an adapter for connecting both of the fans onto one 4-pin header and two doses of thermal compound. It is interesting to point out that the thermal compound is Gelid GC Extreme, a relatively premium thermal paste. The Eiswind fans are PWM compatible, with a sleeve bearing engine and a maximum speed of 1700 RPM.

The Alphacool Eisbaer 240 CPU Liquid Cooler

Even though the radiator of the Eisbaer strongly resembles the radiators of many other AIO liquid coolers, the rest of the assembly is unique compared to any other that we have seen up to this date. To begin with, while the Eisbaer is upplied assembled and prefilled but it actually is a standard liquid cooling kit, as the tubing is not permanently attached on either the radiator or the block/pump assembly. Typical tubing compression fittings are used on both parts that can be undone at any time by the user.

The glossy black tubing of Eisbaer appears to be made out of PVC and has an internal diameter of 11 mm, which is much more than sufficient for a simple system with just one block. A black spring surrounds the glossy black tubing, preventing it from kinking when taking sharp turns. Alphacool also included a plastic connector on one of the tubes, offering the option of relatively quick future upgrades.

The radiator of the Eisbaer may be visually almost identical with the radiators used by many other products. A closer inspection however reveals a major difference: both the channels and the fins of this radiator are made out of copper. This makes the radiator a little heavier and considerably more expensive to manufacture, but it should also offer a noteworthy performance boost. The company logo can be seen printed on the sides of the steel frame.

Eisbaer’s block/pump assembly is quite tall but not very wide, with a plastic body and a copper base. There is a fill tap on the top of the assembly, allowing the user to refill and maintain the system. The company’s logo has LED lights installed and will illuminate blue once the pump is powered on. A little window on the side reveals the pump and fluid to the user. As this would not be visible from the side panel of the case, Alphacool did not install LEDs inside the block.

Inside the assembly we can see one of Alphacool’s pump designs based on the DC-LT Ceramic 12V pumps. The maximum flow is 70 L/h and it has a head of 0.85 m, figures that may not be great compared to those of large external pumps, yet are impressive for such a small device.

The copper base of the cooler is very smooth and appears to have been machined down to a perfect mirror finish. Unfortunately, copper is very easily oxidized and we received one of the pre-production samples that only had a temporary protective sticker attached. It was not attached well and the trapped air oxidized the base of our sample, creating an abstract canvas. This cannot and will not affect the performance of the cooler in any way, it is a mere aesthetic mishap that degrades the appearance of the product.

Our early pre-production sample

Testing Methodology

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 only manually. Fans can have significant variations in speed from their rated values, thus their actual speed during the thermal testing is being acquired 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.

*noise levels above this are not suggested for daily use

Testing Results, Maximum Fan Speed (12 Volts)

The thermal performance of the Alphacool Eisbaer 240 in relation to its noise level output is impressive. With an average thermal resistance of 0.078 °C/W, the Eisbaer 240 does perform about on par with other similarly sized AIO liquid cooling solutions, falling only slightly behind the Corsair H100i and NZXT Kraken X60, and overtaking the Reserator 3 Max Dual and SilverStone Tundra TD02 (first version).

Even though the thermal performance of the Eisbaer 240 is very close to that of these coolers, there is a world of difference in terms of acoustics. The sound pressure level emanating from the Eisbaer with its fans running at maximum speed is the lowest that we have recorded from a dual 120 mm fan AIO liquid cooler up to this date and many dB(A) lower than that of nearly every competitive product. The EKWB EK-XLC Predator 240 is the only dual 120 mm solution that offers slightly better thermal performance at the expense of some additional noise, while the dual 140 mm Corsair H110 offers about the same overall performance but with a 280 mm radiator and larger fans.

Testing Results, Low Fan Speed (7 Volts)

The quiet fans of the Eisbaer 240 have their speed greatly reduced with an input voltage of 7 Volts, down to just 810 RPM. These fans can hardly generate any pressure at such a low speed so, naturally, the thermal performance of the Eisbaer 240 is now reduced significantly.  With the average thermal performance reduced down to 0.106 °C/W, the Eisbaer 240 is now outperformed by every dual 120 mm AIO cooler that we have tested to this date.

Nevertheless, the average thermal resistance of 0.106 °C/W is not actually bad considering that the Eisbaer 240 is virtually noiseless under these operating conditions. Our instruments recorded just 32.6 dB(A) from a distance of one meter, only 2.2 dB(A) higher than our floor noise level and a figure that it is not easily discernible by human ears inside a normal room. It is possible to discern low humming noises only from a distance of a few centimeters away from the fans and/or the pump. 

Conclusion

In this review we had a look at Alphacool’s latest product and first AIO liquid cooler, the Eisbaer, which the company is marketing as an “extremely quiet, expandable solution”. It is true that the supplied 120 mm “Eiswind” fans did perform very well and that the ceramic pump is practically noiseless, making the Eisbaer 240 the least noisy AIO liquid cooler that we have tested to this date. Our only concern lies with the long term reliability of the fans, as while sleeve bearing engines are amongst the least noisy options, they lack the long-term reliability of other solutions that are noisier or expensive.

While the Eisbaer 240 did not outperform every other similar cooler in terms of raw thermal performance, it possibly has the best noise/performance ratio of every dual 120 mm fan AIO cooler available today. It could likely outperform several of its competitors if stronger fans were to be used, but we feel that Alphacool’s choice of fans in terms of noise performance hits the mark. Users can fall into two categories - thermal or acoustic performance, and a user that places acoustic comfort above a slim difference in thermal performance will do well here. Even with its quiet fans, the thermal performance of the Eisbaer is very good and more than adequate for the typical gamer/enthusiast that simply wants a cool and quiet high performance system.

The expandability of the Eisbaer 240 is one of the primary focus points of Alphacool’s marketing team. It is true that the Eisbaer 240 is very versatile, offering expansion options depending on the user’s skill and needs. It has a quick release connector on the tubing for users that want to keep things simple and expand using parts that the company supplies specifically for the Eisbaer, plus the company has simple tube compression fittings installed on every part that allow the user to completely remove the tubing if necessary. The Alphacool Eisbaer 240 practically is a standard, divisible liquid cooling kit that is being supplied preassembled and prefilled by the company.

Expanding the Eisbaer may be a relatively simple process but the user has to take into account the impact that the expansion will have on the performance of the system. For example, the insertion of a GPU block will add both resistance and thermal energy into the system, respectively reducing the flow of the pump and increasing the load of the radiator. A second radiator will offer quicker thermal energy dissipation but significantly burdens the pump. In theory, a single loop can be expanded to cover multiple GPU blocks and more than one radiator but, as the pump cannot be upgraded, we advise against the installation of more than three items per system. It is technically possible to add an external pump into the system but that would beat the purpose of having an AIO solution in the first place, as a customized kit would perform better and cost less at this point. Alphacool has informed us that they are currently designing a similar AIO liquid cooler for GPUs, the GPX-Pro. When the GPX-Pro becomes available, the interconnection between the two system will be possible, allowing them to share their radiators and double the pressure (but not the flow) of the pumps. Whether having the two systems interconnected will perform better than keeping them separated is a complicated discussion that depends on many specific details, such as the CPU/GPU, the position of the radiators, the strength of each pump, the usage of the system, etc., preventing us from being able to provide a simple and definite answer.

Alphacool currently retails the Eisbaer 240 in Europe for €115 incl. VAT plus shipping costs. Slightly lower pricing may be found via some of their local resellers. In the US, the Eisbaer 240 is available for $120 plus shipping. The price is higher than that of most similar competitive products, but reasonably so for a product that offers an expandable setup with a copper radiator and high thermal performance combined with near-silent operation. We highly recommend it to those seeking a low noise AIO cooling solution, especially when there is a significant preference for potential future expansions/upgrades.