Turbo Boost can increase the clock speed of each core individually to get more performance out of the chip.
Basically, if the current application workload isn't keeping all four cores fully busy and pushing right up against the chip's TDP (Thermal Design Power) limit, Turbo Boost can increase the clock speed of each core individually to get more performance out of the chip.
Example: For the Core i7-920XM, that maximum speed bin is 3.2GHz, not the 2GHz value which is marked on the part. In principle, the 920XM could run all of its cores at 3.2GHz all the time if enough power was available and if the heat sink could keep the chip cool. (This is why Turbo Boost isn't like consumer overclocking: the chip is operating within its design specifications at all times.)
Leia o artigo completo:
Explicando a tecnologia Turbo Boost da Intel
Are we likely to need better power supplies and even bigger heat sinks and fans with these new chips?
Suponho que, se você melhorar o resfriamento, poderá aumentar ainda mais os limites com o Turbo Boost, já que ele está vinculado às especificações de projeto térmico.