Cooling

Both cards actually have identical coolers that differ only in size. The evaporation chamber is the key feature: the Vapor-X cooler is based on evaporation of the liquid coolant from the hot surface. The resulting vapor condenses on the cold surface, and then the liquid is routed to the hot surface again. This recirculation occurs inside a vacuum chamber, controlled by a complex capillary system. Vapor-X chambers are very thin, and they are mounted on the GPU to touch the die.

Sapphire RADEON HD 4850 Vapor-X 512MB
This device cools only the core. The evaporation chamber is assisted by a large heatsink with a slow quiet fan in the center.
Sapphire RADEON HD 4870 Vapor-X 2048MB
This device has a larger heatsink plus a passive radiator for the power circuit elements. For some strange reason, memory chips are covered by a heatsink only on the back side of the PCB, while chips on the front side are not cooled at all. I don't understand engineers who install heatsinks just to observe formalities. One should either provide cooling to all components or don't do it at all. What a strange 'one-legged' solution.

As usual, we monitored temperatures of the cards using RivaTuner.

Sapphire RADEON HD 4850 Vapor-X 512MB

Sapphire RADEON HD 4870 Vapor-X 2048MB

Our tests show that the efficiency of this cooling system is brilliant.

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