All modern processors have quite sophistocated throttling (a.k.a. power management).
The CPU will slow down when it’s idle, or when it gets too hot. Even in a desktop PC, the very fastest clock speeds (often called “turbo boost” or similar) can usually only be sustained for minute or so, unless you have some serious cooling.
So, I am slightly dubious about the wisdom of putting a power-hungry i7 processor in a “fanless” case. It won’t overheat, but I doubt it’ll achieve nominal performance unless you put it in the fridge.