Silicon Speed

Temperature increases with increasing switching frequency (the faster you run it the hotter it gets). This is because the transistors spend more "average time" in the switching state (neither on nor off) which is when they really draw current.

Maximum switching frequency decreases with increasing temperature (the hotter you run it the slower you have to run it). This is due to physical effects of temperature on the silicon (electron mobility primarily, switching thresholds, etc). Everything just takes longer to move around when things get hot. So it takes longer for those transistors to change state and it takes longer for charge to travel between transistors.

Decreasing the temperature has the opposite effect. As you decrease (or maintain) the temperature, you create an environment where higher switching frequencies can take place (or be maintained). So if you want to increase your maximum switching frequency, you have to lower the temperature. And of course if things get too hot the physical components of the IC can breakdown causing permanent damage. (I've seen CPU's explode when cooling was removed too rapidly).

This is why you will see hard core PC gamers apply extreme cooling solutions to their processors so that they can achieve extreme overclocking.

Does this help?