If I had responded to the survey and answered only what it asked, My 3800x would be listed as one of the CPU's that can't hit rated boost clock.
The problem is, and this is important to this discussion, **my CPU hits rated boost clock,** (even a little higher sometimes. )
So when people use this survey to say that "most chips don't hit rated boost", I think they are making that statement with insufficient data to back it up.
My 3600X was tested as per Roman's instructions and the results submitted so they're part of the figures he reported.
2 cores boost to 4350 (the uppermost of the two large peaks in Roman's 3600x frequency distribution)
2 cores boost to 4300
2 cores boost to 4275
The cores peaked at exactly the same clock frequencies in the single core CB R15 test as they do when the system is left idle / used lightly loaded for a few minutes (at default/Auto voltages max VID is 1.45volts, which the Asus BIOS AUTO voltage implementation respects).
With the limits the current SMU firmware component from AMD imposes, nothing I've tried so far causes the processor to boost any further than 4350.
Being 50MHz shy of the advertised 4400MHz, matters less than not having the ability to trade some of the stability margin AMD builds into its VID table of each processor to reduce voltages, and hence temperatures, whilst maintaining clocks/performance.
At the moment, any meaningful undervolt I apply drops the multiplier by 0.25-0.5 and worse, initiates "clock stretching" seemingly to maintain the stability margin, so I'm losing a bit of performance even with a mild 43mV undervolt.