Mine doesnt lock and crash @ 940-950 (depends on the cards) / 300, with standard (1.088V) voltage (it's a sapphire extreme non-ref)
What brand is it? Reference or non-ref?
its an OEM Reference. I also have a visiontek reference running at 920/500 on another box doing 370 on 11.6 and 2.4 sdk. it seems really low to me