OCC has published a review on the Sapphire HD 5770 Vapor-X Overclock Edition

The Vapor Chamber cooling kept the Sapphire HD 5770 Vapor-X down at 64 degrees Celsius under load during my overclocking testing with the fan speed at 90%. Letting the drivers control the fan speeds at the stock clock speeds the core temperature never hit 75 degrees Celsius under load. During this testing the fan speeds reached only 56%. This kept the temperatures as well as the noise in check. So you have a win/win situation where you get lower temperatures with much less noise than the reference cards.

Sapphire HD 5770 Vapor-X Overclock Edition Review