Weird CPU behaviour

Question

Occasional low performance & considering the frequency, I'd say it's more of an occasional high performance.

The maximum CPU speed is 2.20 GHz.

Most of the time, my computer becomes very slow and the CPU frequency goes up to no greater than 0.6~0.8 GHz. At other times, the frequency is 2.7~2.8 GHz (weird but makes me happy).

What could be the cause?

Thank you.

EDIT: I meant two things:

1. The speed goes over the limit.
2. It gets stuck in low frequency even when I require it to give more (by using several CPU extensive applications)

EDIT 2: It's a laptop with Intel Core i7-2670QM CPU @ 2.20GHz

EDIT 3: Thanks to David Schwartz, I know that:

1. The CPU will go over the maximum labeled speed under some conditions

2. Overheating might cause the CPU to NOT reach the needed speed

Although in my opinion it didn't get too hot. I'll observe the CPU's behavior for a while.

Answer 1

That is a feature of the CPU. It regulates the speed. If it needs more power, it uses more power. But if you for example just read a Word document, you don't need this speed and the CPU will use less.