As the point of this article is to look at the performance of each card when overclocked it is worth going over the choice of clock speeds used. For the GTX 570 we have gone with the highest overclock currently available on a retail card, 840MHz core with 975MHz memory. For the 6870 we are making use of a factory overclocked model which uses 940MHz core and 1150MHz memory, bumped up to 970MHz on the core to match the fastest retail version we have seen.
The 6950 card on the other hand do not currently have any decent overclocked retail models to base the testing on so we have set it to their maximum rating available in Overdrive. We also increased PowerTune to its maximum setting. This gives us a core 840MHz with memory at 1325MHz.
Finally for the GTX 560 we used the stock speed of 950/1075MHz as that is actually the fastest retail Ti card we have seen to date.