Everyone has heard of Turbo Boost, as it is one of Apples most prominently displayed specifications about their computers, but I have no idea WHAT exactly it is. Does it mean they can be overclocked to get to that speed? Does it mean when it is plugged in and has enough battery it will run faster? Do I have to manually turn it on? How? What triggers it? I have nearly zero understanding of what it is and how it functions, and would really appreciate some insight.
This isn't something unique to Apple, it is pretty complicated but I'll try to summarize it as short as possible. Essentially when a silicon chip is made its position and the grade of the wafer is done similarly to how diamonds are graded. Chips cut from the edge have higher impurities in the silicon than the ones in the center. So this concept of "overclocking" is not doing anything mysterious per say it is simply running the chip at it's natural ability rather than being grouped together.
Once the wafer is cut they are binned based on grade, higher grade units are capable of running with a higher speed frequency than ones that are not. These grades are done in tiers of basically good, better, best and that is how they determine what chip becomes what speed, name etc.
Mobile chips tend to be the highest grade since they need to perform under adverse conditions and Intel is taking advantage of that. So what they do is decide a bell curve of what the chips are capable of running and set standard deviations plus or minus of what on average each grade is capable of and bin them accordingly based on wattage.
So if grade A or whatever they want to call it produces 100W of heat with 1 core and 1 thread at 4ghz but two is over 100 watts then again they being intel figured out what the next level would be at that wattage and so on.
So when you fire up a game and it only needs one thread your CPU jumps to 4ghz, then 3.9, or 3.6 down to the "base" frequency of last resort before it takes critical action to shed heat and shut down to prevent from over heating. I know that's a bit wordy that is how it works.
All of this is hard-coded to the chip's internal design and no changes have to be made for it to behave like this. The reverse is also used to save battery power so that the chip uses only what is necessary to run a program.
The vast majority of time your chip will be in the 800-1200mhz range and will jump to 3.7/3.3 only when necessary to conserve power