My EVGA KO was getting to hot and crashing games... card runs at 675/1950/1674... temps without adjusting fan speeds... (before rivatuner) idle @ 60-62c, load 70-95c (depending on app.) I have Thermaltake large case good airflow, cpu runs in low 30's and sys 40's.
I had to use Rivatuner to auto adjust the fan speed in these increments (these temps keep it cool and help keep ambient temp cool in case, I could bump temps up but I like it cool):
Fan Speed > Temperature
29% when temp is < 62c (this is the default auto speed)
40% when temp is > 62c
60% when temp is > 68c drops to 40% when temp hits 62c
80% when temp is > 74c drops to 40% when temp hits 62c
100% when temp is > 78c drops to 40% when temp hits 62c (it as yet to go above 76c so I never see the fan run at 100%.)