It would seem to have to be a heat/current issue, since the only practical thing to compromise circuits in a physical nature. Adjustments to these type of chips is usually in steps (not a like an analog potentiometer), so seems the only thing they could do is either turn gates off to silicon not be used in the chip (probably none to turn off), or step down the power, which could mean a slower device. Depending on the array set up for the radios, they can also step those down, but also would be a likely performance decrease.
The red rings of death on the 360 was fixed by shipping with a modded board- not a firmware change. Some capacitor/resistors were too close to the GPU and slowly fried. Well, "popped" could be a better word.