ever considered crossfiring the 6870, I got 2x 6870's with my I5 3570K and they are keeping the CPU at load..... I would only upgrade with series 9xxx , skip the 8xxx series and most likely go for 9970 single card to replace both of my 6870's. But once when I go for 9970 I would have to OC the CPU to 4.3Ghz which it does on stock voltages!!!!!!!!!!
Think about it m8, 6870 in CF scale better than any card out there, AMD hit right on the money with the 6870's, look up charts it practically creeps really close to to 6990 which is a dual 6970 with slower speeds.