"Although on paper the Sapphire HD 5770 FleX appears to be just a reference designed 5770 with a different heat sink, it proves that it is much more through the overclocking headroom and how cool it operates. Being able to benchmark at 1 GHz core is not an insignificant feat, especially without voltage modification. The core was tested with a 15% overclock and the memory tested with a 13% overclock, not bad at all and there was the possibility for more headroom with enough patience."

Sapphire HD 5770 FleX Review @ OCC