The temperatures of the Radeon HD 7850 were within safe limits at load, and it idled with low temperatures. The problem with comparing GPU temperatures comes down to the performance of the cooler, which is generally comprised of a heatsink and fan. An open variable comes from fans. Fans in the coolers of video cards are usually setup with variable speeds. When the temperatures are higher, fan speeds are higher ... and vice versa. I'll touch on that shortly when discussing noise. Just leave the GPU temperature section knowing that the Radeon HD 7850 was installed with a capable cooler.
Thanks to the new 28nm manufacturing process, the Radeon HD 7850's power usage was significantly lower than the last generation 6870. At full load, it was a full 20% lower. Likewise with idle load, power usage was lower.
Ending this section with noise, I don't yet have a standardized practice in place studying the noise output of hardware. But after using the Radeon HD 7850 while gaming, I do have some subjective observations. When idle, the cooler is essentially silent. With the load of an intensive game, things change on the noise front and the fan speeds up.
The cooler on PowerColor's reference design Radeon HD 7850 is pretty small, so the fan needs to ramp up to provide adequate cooling. When playing games, this results in a moderate hum. It's quite at an annoying level of noise, but it's definitely noticeable. The noise to cooling balance of the cooler is set well, as you can see from the temperature graph above that the GPU temperature is allowed to reach the 80 degree celcius range before the fan speed ramps up noticeably.