APACK, the Korean Company, covering up the brand Zerotherm, is a relative newcomer on our market. It has been eight years, since the Company was established by three skilled engineers, extensively concerned in thermal technologies. They started like OEM, and after releasing the first Zerotherm, the Company has changed to a valuable worldwide producer. Since then, complete assortment of Zerotherm coolers for processors and graphic cards is already available on our market. For the moment the most efficient VGA cooler among the VGA coolers of APACK Company is GX815, and this is going to be the last competitor in today’s comparative roundup.

The APACK philosophy is not only creating efficient cooling solutions, but also the high quality of design. Zerotherm is trying to captivate all potential users with fancy but effective packaging. In this spirit, Company has created also casing of GX815.

The cooler is placed into a silver cardboard box, with colorful printing and big clear window where you can see the cooler and other accessories enwraped in a clear plastic tray. Casing is not only attractive, but also safety protection. The manipulation with pack is very simple, as there is plastic carry handle on the top of a box.

Besides the heatsink GX815, in the pack you can find: eight aluminium RAM heatsinks, thermal grease, detailed and illustrated users manual and two sets of screws and nuts. First set of mounting hardware is for installing the cooler entirely by hands without any tools. Second set of screws and stand-offs serves for installation of GX815 on two graphic cards, NVIDIA Sli or ATI Cross-Fire. The two-cards system installation requires a screwdriver.

Technical specifications of Zerotherm GX815:

From technical specifications listed above, Zerotherm GX815 appears to be quite similar to Zalman VF900-Cu. Values of fan speed rotation, as well as sound level are very close. Two coolers have nearly identical weight and beraing type is the same.
At first glance, you have impression that these coolers are twin-brothers. Of course, there are few details, in which Zalman differs from Zerotherm, but I cannot suppress the feeling, that APACK Company was strongly inspired by Zalman.

The biggest difference is in fan construction. Fins are adjusted to fan design, concentrated in the part with heatpipes - place with the biggest air fluctuation, and do not extend under the fan. Principle of construction of heatpipes is visually identical with Zalman model. But in detailed look, you can see that althought heatpipe is the same round shaped, GX815 uses only one heatpipe, which is attached to the base.

120 copper fins remind butterfly wings, and are according to me a design piece. I hope this indicates a new line of products and Zerotherm will apply this motive also in future models. In the upper part of plating, there is a signature of manufacturer, making the cooler even more impressive.

Cooler is beautifully shaped and elaborated on superior quality. Single copper plates are precisely cut, with all edges rounded. Copper fins are soldered to the heatpipe, whereas the point of connection lies underneath the heatpipe, like that, on the upper part of plating, there are no visible traces of tin. You can see very exact and detailed elaboration. Point of connection is rather small, however, even under bigger pressure the whole construction shows solid stability. The overall steadiness is supported with high-quality moulding.

The base of GX815 strongly resembles Zalman VF900-Cu. The heatsink is nearly identical with Zalman – the same round shaped contact area of similar proportions, identical mounting modul with multi-holes system. There are slight differences in a way of soldering of two parts composing the base; the fact is, that spider-shaped mounting modul is not as elastic as Zalman’s modul is. There is another little difference; the contact area is protected with transparent foil with printed warning, which is quite useless in this case.

The most marked difference is hidden inside the heatsink base. Two black wires, indicating thermal sensor. Thermistor allows the fan to regulate its speed according to the GPU temperature registered by the sensor. Fan speed changes with temperature nearly with direct proportionality. It is not possible to turn thermistor off, and to regulate fan speed manually, and I guess, certain group of users will not like it. You can adjust input voltage on 3-PIN connector, and influence maximal speed rotation. Even like that, sensor is going to regulate fan speed, up to the adjusted maximal speed rotation level.

Underneath the protection foil you can see perfectly polished copper base. I have found the quality of its elaboration on slightly lower level, comparing to perfect Zalman VF900-Cu.
Also my impression after using the cooler was not very positive for Zerotherm. Copper base got markedly darker on certain spots, already after first testing, while Zalman’s copper base resisted multiple installations without any changes. This little drawback does not affect GX815 functionality.

It has been already mentioned that the biggest difference between GX815 and VF900-Cu is in fan construction. VF900-Cu fan has shifted wings and presses the airflow through the heatpipe in the direction of graphic card. GX815 has plane wings and relies on the heat absorption from the copper base through the heatpipe to the fins. Like this airflow is directed on a desired place, and effectuality of cooler is growing. This way of active cooling has its disadvantages, as the airflow does not pass through certain parts of graphic card. In this case, RAM heatsinks and voltage regulator are going to be cooled only by small aluminium heatsinks.

Radially shaped, 15-wings fan - SFC6025HB-12T with diameter 68 mm is made by Chinese Silentmatic. I was not able to find detailed information, all we know are technical specifications mentioned by Zerotherm, and data on a product’s tag. Fan speed rotation, from 1200 to 3000 rpm, is controlled by thermistor. The noise level is from 18.5 to 33.8 dBA. In my opinion, the upper level is rather high, and not acceptable for most of the users. For this reason I guess that in reality not many will enjoy maximal airflow 11.1 CFM.

The shape of fan wings - with blue lightening - is adjusted in a way, that airflow can head to fins. Wings are plane, their shape is gradually broadening, and the upper part of wings is as broad as plate of fin. There is plastic circle, placed underneath the whole surface of a cooler, which blocks heat absorption from graphic card surroundings. This allows the fan, to take in only the airflow from the upper part.

Installation of Zerotherm GX815 is, as it was in three previous cases, very easy. Process of installation is identical with Zalman VF900-Cu. First is neccessary to stick little RAM heatsinks. I have to say, that Zerotherm RAM heatsinks have unique design, they are not only efficient, but beautiful green pieces of aluminium. Next step is application of thermal compound and placing of the screws into the proper mounting holes. After placing the screws through the mounting holes it is needed to tighten the thumbnuts down until bottom.

Once the cooler is placed onto a graphic card, you can notice that GX815 takes much more space than VF900-Cu. This is due to the construction, fins are placed on the margins of the cooler, and like that, they are broadening the whole structure. The cooler is fixed and secured on four places, that makes it very stabile, also its pressure is sufficient.