I'm wondering if I'm around target for a 5850. I am getting a stable 372 kh/s out of each card. I try to OC gnu to 900 and memory to 1175 and one of my two cards goes sick and then dies.
https://litecoin.info/Mining_hardware_comparisonAccording to this you're a good bit ahead of the average hash rate for the 5850. Of course the cards will vary themselves, just OC them individually as much as possible and find the stable plateau?