To test the temperatures of the Sapphire Vapor X 5750 I fired up FurMark 1.70 and GPUz. Running FurMark at a resolution of 1024x768 was more than enough to bring the work load to 100%
All temperatures were taken with the fan control on auto. Starting out at 54 degrees is a reasonable temperature. The HIS Radeon HD5870 does use the reference cooler on it which did a good job leveling out the temperature once it hit 86 degrees.
Benchmark Results: The HIS Radeon HD5870 was the hottest card that I tested. It is also the fastest card that I tested. If you don't mind a little bit of extra noise you can always bump the fan speed up to cool the card down better.