The described product is equipped with a reference cooler, so everything we will say below refers to every other reference-design Radeon HD 4890.
The reference cooler of the Radeon HD 4870 card is far from being an etalon in terms of noise and efficiency, yet the Radeon HD 4890 developers have employed it with but minor improvements. The cooler implements the same concept as Nvidia’s reference coolers but, unlike them, has a much smaller heatsink.
The cast aluminum frame is not connected with the main heatsink mechanically or thermally and only serves to dissipate the heat from the power circuit elements and memory chips. It is also the basis the fan and the plastic casing are fastened to. The frame has a strip of some green fiber material at the places of contact with the voltage regulator’s power drivers and multilayer elastic pads for the memory chips.
A rather small heatsink consisting of thin aluminum plates is installed on the massive copper base that contacts with the GPU die through a layer of dark-gray thermal grease. It is connected to the base with three heat pipes: one pipe more than in the Radeon HD 4870 cooler. The heatsink is cooled by a 12W blower CF1275-B30H-C004 from NTK Technologies which is very loud at maximum speed. As usual, the hot air is exhausted out of the system case through the slits in the graphics card’s mounting bracket.
The base of the cooler is fastened to the PCB with ten screws. The GPU heatsink is fastened separately with four threaded poles and a stiff X-shaped metallic back-plate with spring-loaded screws. There can be no misalignment that might damage the GPU die. Moreover, the heatsink cannot be accessed from the outside – it is covered by the plastic aerodynamic casing.
At first glance, the cooling system we have just described seems to be good, but we think the heatsink is rather too small for an RV790. We have apprehensions that the fan may have to work at a high speed to keep the temperature low. We will check this out in the next section of the review, though. And we also hope that graphics card makers will come up with alternative and better coolers for their versions of Radeon HD 4890.