There's a side benefit to this as well, your cooling solution is more effective at 90C than it is at 40C, you know, highschool physics, deltaT and all that.
That also comes with the side effect that the transistors are leakier at high temperature, leading to higher power for the same performance as compared with operating at a lower temperature. This effect is significant: in mobile systems it can easily be the case that turning on a fan (or speeding it up) leads to a net decrease in power consumption because the power saved by making the chip less leaky is more than the power spent running the fan.
