Err, no, actually. it really is clocked down, and that's what intel says.
There is the normal base frequency (which is, again, the one people see on the box. Intel calls it "marked TDP frequency")
There is the avx base frequency, which is less.
If you execute all avx workloads, it will clock down to the avx frequency, which is below the marked tdp frequency.
They are very explicit about this: "Workloads using Intel AVX instructions may reduce processor frequency as
far down as the AVX base frequency to stay within TDP limits."
