Precison 3551, Turbo Boost on Intel i7-10875h

Question on my brand new Precision 3551  15 inch: i7-10875h 8/16 cores, maximum Turboboost 5.1 GHz.

Both in Windows and in Linux (the latter being my primary OS) I am unable to hit the 5.1 GHz. In Win 10, cpu-z benchmarks top out at ~ 4.6 GHz and in Linux it tops out at 4.4 GHz (intel_pstate = powersave) or 4.8 GHz (intel_pstate = performance).  Also, in Linux the 'cpuid' tool does NOT report Turbo Boost Max Technology 3.0 whereas the Intel ark site clearly states that it does support it.

What can I do to troubleshoot this? Note that I am doing my tests on a  well-cooled idle system.