Imagine you have a CPU with 4 cores @ 2.2GHz, each one with a thread. Therefore, the OS thinks that it has 8 cores @ 1.1GHz each (I think).
What would be the maximum GHz that a not concurrent program could use? 1.1GHz? Or 2.2GHz?
No, it does not. There are 8 virtual cores with 2.2GHz. A program could use 2.2GHz or more in case Turbo Boost is on. Although technically programs don't use frequency like that, a program running on only one virtual core (one of the eight cores) and using 100% of it (12.5% of total CPU) would practically be using a 2.2 (or more) GHz core.