downstairs said may be correct.

Intel and AMD uses dynamic frequency and core voltage to extend battery life, and be more green. Do you really need 2.8GHz to browse?

But, from all my systems, the lowest frequencies it get is 1/2 Fmax, so your 1/4 Fmax is kind of interesting. Maybe your board got this improved?

For laptops, this truly extends the battery life. Strongly suggest not to turn it off.