75c with fan at 47% on Auto is completely normal. People tend to overrate what they consider overheating and don't realize that the card is engineered to run at a certain target temp. In this case 80c+ is the target. I bet your card was nice and quiet at 75c, which is exactly what the engineers preferred over unnecessarily cool temps.
This is from a review that used a closed PC case (most reviews use an open case, which runs cooler). As you can see, under normal Auto fan operation, a GTX 670 is going to go up to 81c with the fan going as high as 57%. With overclocking or something wrong with the card, that temp of 81c will remain more or less the same, while the fan will adjust higher to maintain that target temp. You can adjust your fan for lower temperatures, but it's unnecessary and will increase your noise levels.
http://www.xbitlabs.com/articles/graphics/display/geforce-gtx-670_2.html#sect0
And overlocked, more or less the same temp, but a faster running fan.
If My gpu reached 100 degress 3 times for about a minute and caused my card to throttle would that damage it and keep in mind this is 3 times just a question please reply?