Overclocking
To find the maximum overclock of our card we used a combination of AMD internal overclocking software, ATITool and our benchmarking suite.
The final overclocks of our card are 793 MHz core (2% overclock) and 1097 MHz Memory (10% overclock). The core overclock is limited, but you also have to see it in relation to the reference clock of the RV770 core which is 750 MHz (6% in that case).
Temperatures
The temperatures of the Palit HD 4870 Sonic Dual Edition are very low, but the fan is noisy as well. I would have preferred some kind of compromise between fan noise and low temperatures.