The ZM-GWB1 is not just a water block for the graphics processor, but rather a cooling kit for the GPU as well as the memory chips on the graphics card.
The kit consists of two water blocks, eight heatsinks with sticky thermal pads for the memory chips, fastenings, a small tube with thermal paste and a screwdriver.
The water blocks look alike. The longer of them fits for almost any graphics processor, and the shorter is intended for GPUs with a protective frame around the die, for example for RADEON 9700/9800 series chips. Thanks to the well-designed fastening system, the water blocks can mount on nearly every graphics card. The only requirement to the card is its PCB must have suitable holes near the GPU.
Although the nozzles the connecting silicone tubes are attached to don’t look assuring, the tubes do hold tight– it’s hard to take a tube off such a water block without a serious effort.
The internal structure of the water blocks is disgustingly oversimplified: there are no grooves, cavities or ribs to improve heat transfer to the water stream. Instead, there’s just a trivial through hole that comes straight from one nozzle to the other:
I must confess I hadn’t expected anything like that from Zalman. Without running any tests, I can already express my doubts about the efficiency of such water blocks. First, the sole surface of the blocks is not treated at all. Thermal paste can improve this somewhat, filling in the micro-caverns on the anodized surface, but some polishing off would anyway help a lot. Second, the heat from the graphics processor is not transferred through a copper base, like in Zalman’s own CPU water block, but rather through a thick layer of aluminum, which has twice worse heat conductivity characteristics. Lastly, a through and round hole is the worst channel for the water stream. Such a channel has the smallest internal surface area, i.e. this is the worst case for heat transfer.
It is good the ZM-GWB1 doesn’t come with Reserator 1 – it wouldn’t do to spoil such a nice system with a bad GPU water block.