Below is provided by @n_scott_pearson
4.7GHz is your processor's Maximum Turbo Boost frequency. You are only going to see boosting to this frequency when (amongst other things) your processor has the thermal headroom and only a single core is active. If (amongst other things) the processor is too hot or more than one Core is active, the maximum frequency possible will be lower.
I said 'amongst other things' a couple of times. This is a complicated subject and, if you really want to understand it, you are going to have to spend some time reading about it. As a starting point, try these resources:
What is Intel Turbo Boost Technology and How Does it Work?
My Intel Core Processor Does Not Reach the Maximum Turbo Boost Frequency
Frequently Asked Questions for Intel Turbo Boost Technology
Frequently Asked Questions About Temperature for Intel Processors
Doc (not an Intel employee or contractor)
[Fear and the desire for control are primary motivators for shadow dwellers. ]
