[knc1]

And if you check, it probably has the "conservative" governor enabled.

Often the kernel will have more than one of the governors available, you should be able to get a list of the ones available in that general area of the system tree.

You can also switch governors by writing instead of reading the "current xxx" (forgot the name) entry.

As you browse with ls -l, keep an eye open for the things that are write enabled, you can change all of those.

PS: Yes, all of this goes towards an answer of the question asked:
"Under what conditions?" should have been included in the question.
The answer is: 60Mhz ... 800Mhz, depending on ..., which is a very large range.

(I think the minimum on the SoC is a few hundred Khz - but the kernel may not run that slow - you may have to check the "power" part of the sys cpu tree - look for a "sleep" entry (or some such) - that will slow it way down, but you may have to re-boot to wake it up.)