you can go past the 950/1450 limit using an Asus card bios and the latest Smart Doctori'm wondering how to overclock the card past its limits now; the only method i know of is RBE but after flashing the driver doesn't recognize the card any more...
you can find asus 6970 and 6950 bios's in this thread
http://www.xtremesystems.org/forums/showthread.php?t=264107
but the overvolting doesn't seem to work