Turbo Boost is the term that Apple very proudly boasts of about its processors. The term actually was invented by Intel. In certain versions of Intel processors, they can run over their clock-speed to give an extra performance and faster speed. This is called Turbo Boost.
MacBooks have this feature. When the laptop is lightly loaded, all of its cores are not in use; the processor shuts down the unused cores and in turn, increases the clock-speed of the used cores. That is of course, if enough power is there and the temperature is at a safe level. This gives a dramatic increase in the processor speed. For example, the 1.8GHz i5 processor can be pushed to around 2.9GHz. The custom option 2.2GHz i7 processor can reach upto 3.2GHz through Turbo Boost.
How to use Turbo Boost
Whether or not you should use Turbo Boost depends on the following factors.
- Number of active cores
- Estimated current consumption
- Estimated power consumption
- Processor temperature
In many CPUs, you have to manually enable Turbo Boost and then if the above factors allow, it is enabled. However, in MacBooks, Turbo Boost is enabled automatically whenever it is possible. This may have certain disadvantages too like you may want a longer battery or you feel that the laptop is heating more. In such cases, you may not want the additional boost but you can’t manually disable it.
Let’s take the example of 2011 MacBook Air with the 1.6 GHz Core i5. The “Turbo Ratio” is set to 0047. The number represents the amount of boost that different cores of CPU can get (4 cores = 0, 3 cores = 0, 2 cores = 4, 1 core = 7). This is a dual-core CPU, hence 3-core and 4-core modes don’t apply here. The number shows 100 MHz increment. So for Macbook Air (2011), the boost that can be achieved is:
1.6 GHz + 400 MHz = 2.0 GHz, if 2 cores are running
1.6 GHz + 700 MHz = 2.3 GHz, if 1 core is running
Turbo Boost on Wikipedia