Aside from the shape of their cooling blocks, the Arctic Accelero Xtreme III and Accelero Xtreme 7970 are essentially identical.
In the shot above, the top cooler is Arctic's generic Accelero Extreme III, flanked by its bundled accessories. The bottom unit is the Accelero Xtreme 7970, surrounded by its complementary hardware. Clearly, the cooling blocks are different.
Both products share similar accessory packages, with a couple of notable changes. The Accelero Extreme III comes with more memory heat sinks to accommodate a wider range of cards, while, for some reason, the Accelero Xtreme 7970 includes a mixed thermal adhesive that requires a catalyst. The fan power cable is designed to plug directly into the graphics card, so the driver software can alter the RPM in response to the thermal load.
A closer look at the 7970-specific cooling block makes the functional difference between these two products even more apparent. Radeon HD 7900-series cards require that the GPU contact area be raised from the rest of the cooler to clear a thick protective shim. The contact area is also turned 45 degrees to match the graphics processor's orientation on the PCB. Both Accelero Xtreme models come with thermal paste pre-applied.
Mounted atop a reference Radeon HD 7970, the card’s dimensions become 12.5 inches long, five inches thick, and 2.25 inches deep. The board weighs in just over two pounds, too.
The assembled graphics card and cooler are just wide enough to chew up more than two expansion slots. AMD's reference cooler already makes the card 11.5-inches long from the factory. And while adding another inch doesn't seem like a big deal, you're going to find that smaller cases simply cannot accommodate the extra length. Enclosures with removable drive bays because particularly attractive here.
The Accelero Xtreme III employs three 92 mm fans and five heat pipes, which are enough to handle up to 300 W of heat dissipating, according to Arctic. Both heat sinks are built on copper cooling blocks and copper heat pipes that run through aluminum fin arrays. Although the fan shrouds are plastic, they're surprisingly sturdy.
Installing the Accelero Xtreme 7970 is easy, despite the perceived difficulty of swapping graphics coolers. First, mix the thermal adhesive and catalyst, apply it to the RAM and VRM heatsinks, and attach them to the card. Next, put the heat sink mounting hardware in the right place on the bracket, and attached that to the card as well.
The Accelero Xtreme III is a little more difficult to install because you have to use EKWB's copper adapter. We found that it was easiest to apply thermal paste to the adapter, place the shim on the GPU, and plop the cooler on top of that.
Arctic's Accelero Xtreme has the same circuit board clearance to the left and right of the GPU. In comparison, Deepcool's Dracula is higher on the right side, and less so on the left. In both cases, though, the vendors require that you glue heat sinks to the voltage regulation circuitry and RAM modules using adhesive, making it difficult to switch them out. As a result, we used Deepcool's low-profile sinks on the memory to the left of the GPU in the name of compatibility.
Here is how the cooler looks installed on a reference card and plugged in to one of our test beds. Because it's so long, the cooler sticks out pretty far beyond the right side of our ATX motherboard.