I have a small problem since I bought my new HD 6950. When I try to watch any youtube video while mining the computer freezes and I have to restart. Is this normal or is there something wrong with my new card?
Secondly, with the latest guiminer 20110701 the mining speed decreases in my case by 5 Mhash/sec. Lucky I still had the other version.
Too few information..Do you monitor the card's temp? CPU and memory clock is default? Underclock the memory(use msi afteburner) to about 320 to 350 mhz(try different values each card is different) to decrease the temp. Then you can try to overclock the gpu to get better MH/s values.
Try few versions of ATI SDK and graphic drivers too.