Blame is falling on TSMC. The company’s 7 nm fab may not be producing enough CCXs (physical core clusters) capable of hitting the advertised, 4.7 GHz max boost clock.
Each Ryzen 3000 processor comes in discrete chips. One cIOD from GlobalFoundries’ 12nm fab for the I/O, and one or two CCXs from TSMC’s 7nm fab. The Ryzen 9 3950X, with a total core count of 16, requires twin CCXs in complete working order – and capable of reaching 4.7GHz max boost clock.