Can the program determine the frequency of the CPU or is it impossible? In order to understand the question, imagine a simple situation. Alice tells Bob that her CPU's frequency is X Hz. Bob does not take her word for it. Bob can not meet with Alice and check what frequency her processor really has. Can Bob send her a soft program that accurately determines the frequency of Alice's CPU? Is such a program possible or not in principle?
In these days of superscalar, multicore, virtualisation, power scaling, managed operating systems, and so on, what does "CPU frequency" even mean? 

Note that it may be possible for Alice to convince Bob that she has compute power capable of performing X operations of a known type in a given time, as you find in a proof-of-work system. If it is a problem for which parallel algorithms are believed not to be feasible, he may be convinced that it happened on a single compute device, and not (say) a cloud or cluster.

But for all Bob knows, Alice may have an asynchronous device which doesn't even have a clock speed.