Oookay, I'm a little late posting this one, but overclockers Elmor and Kinc spend some quality time with the ASUS HD5870 Matrix and managed to overclock the graphics card's core to a stunning 1525MHz!
That's an increase of almost 80 percent compared to the reference model, and the memory was overclocked to a more modest 4900MHz. The system was stable enough for 3DMark Vantage, and posted a 3DMark score of P29342 (GPU score 26691).