Overclocking is not an exact science. For example, every GPU is different and just because your friend's HD 5870 hit 1000 MHz doesn't mean that yours will, even if using the same settings. Many factors can influence what a graphics card is capable of, including complementary components like power supply and cooling. Additionally, user experience comes into play while attempting to find a stable overclock.
We expect the type of consumers interested in these products to get the most out of their investment. While it may seem outrageous for some, raising the frequencies on pre-overclocked cards could land you even more performance than already available. For this testing, made use of the overclocking utilities provided with the cards, except for the Turbo X which did not offer one. Instead, we brought up CCC and raised core clock there.
It seems Gigabyte conducted the most aggressive binning process in finding the GPU's with the most overclocking headroom. We were able to push the Super Overclock to a frequency of 1034 MHz, which is an additional 9% over its default speed. And once we finished with the Afterburner mod, the Lightning was able to hit 965 MHz. Admittedly, we expected more headroom from MSI's top card, considering the upgraded 8-pin power connectors and enlarged PCB design. At this point, we can only assume that extreme cooling will be able to unleash the overclocking potential of this product. Since the Turbo X was limited by CCC, it only reached 920 MHz. Until a third party utility us to modify the settings on the Turbo X, that is the highest we can go.