Connect3D X850 XT 256 PCI-E
 

I tried numerous combinations of overclocks and found the best performance at 560 core and 1188 memory. Now I could get the GPU up to 590 mhz but at that speed the memory wouldn’t go any higher than 1140 without any artefacts so I dropped the GPU back to 560 mhz and took the ram to 594 mhz (1188 effective).

Link: http://www.xtremecomputing.co.uk/review.php?id=181