I just got a brand new MSI GTX660Ti OC PE. While at full load (Far Cry 3 on Ultra) it heats up up to 80-83c. I am not manually overclocking it. Fan is on auto. I also have side panel fans (two of them).
It is seems little too high for me.
When I manually set the fan to 55-60% it cools the card down to 72c or so, but it gets noisy.
Its not overheating... Yes it is hot tho. Remember you are pushing the card pretty heavily with all those graphics settings on high. (Whats your resolution?) If you got a second card they could share the load and generate less heat or turn down the graphics settings that dont make too much difference to the overall visual effect like turning down your anti aliasing and shadows etc. You also should have got a card with a better aftermarket cooler like the Asus GTX 670 Direct CU or Gigabytes version of that card. My mate is running his ASUS on a high overclock all settings on high on Borderlands 2. Looks awesome and it doesnt get over 65 degrees and we're in summer in australia.