Hi,
It's almost IMPOSSIBLE for your graphics card to overheat.
It will throttle the frequency and voltage as needed to prevent overheating.
You should investigate GPU BOOST 3 for more info if you want:
http://www.hardocp.com/article/2016/05/17/nvidia_geforce_gtx_1080_founders_edition_review/5#.WE-NTIWcFoU
"This graph shows the temperature from a cold start of the video card so we can see how quickly it ramps up to maximum temperature. The video card takes about 5 minutes to reach its maximum temperature of 83c"
*Your card will generally get to a specific temperature and STAY THERE. What temperature (and frequency) that stabilizes to depends on the card you own, your case cooling setup, and the ambient room temperature.
In general, there's not much to worry about in terms of overheating.
If you want maximum performance you can fine tweak voltage/frequency and/or raise the fan speed in the fan profile, but don't expect big changes there.
(A side case fan can be useful. I have the space for one on the side panel and can feel a lot of HOT AIR coming out of there so even without a fan I'm helping to reduce the temperature... the fan is pushing air towards the card, then it's bouncing off and a fair amount is coming out the mounting area for the fan)
EVGA Precision has a voltage/frequency curve you can set to "MANUAL" then wait several minutes for it to optimize. I believe it sends data to the GPU at a specific frequency/voltage until data corruption then backs off so it can optimize the voltage for each frequency point.
Lower voltage means lower temperature which in turn allows a higher frequency to be maintained longer.
(If this is all gobblety-piggly hooblewash to you then just know chances are you're getting most of the performance already and that temperature likely isn't much of an issue unless you have poor case cooling and/or you are in a very hot area... and then it's more about lost performance due to THROTTLING not an issue with a card failing.)