I have a sapphire 6850 2gb. The stock core clock is 775 Mhz and the memory clock is 1000 Mhz. I Overclocked the core to 850 Mhz an the memory clock to 1200 Mhz. On full load the max temp is 74 celcius. The average is about 60-69 celcius. Are these temps safe? I've heard you don't want to go over 80 celcius. Btw the voltage is stock. I do not plan to up it.