The Xbox One is aware of the current temperature it is running at and is able to take action to cool itself down. The unit will first start by pushing up the fan all the way to its maximum speed – although Microsoft does not anticipate the need for the unit to do so under normal environmental conditions.
If after increasing fan speed, the unit still does not cool down, the unit will be able to switch itself to a lower power state in order to protect itself.
We are currently unsure of how the under-clocking works and how it might affect game performance. Although as stated above, this is a last resort for Xbox One and should not occur under normal environmental conditions.
Sent from my Windows Phone