Looking at clock speeds for the Ryzen 7 5800X3D, we noted a 4.4GHz typical all-core speed after a 10-minute looped run of Cinebench R23. The boost clock that we observed peaked at 4550MHz but was more often 4450MHz.
These speeds are around 150MHz below the Ryzen 7 5800X for all-core loading, and around 200-300MHz less for maximum boost frequency. But the new 3D V-Cache equipped chip was running at significantly lower power levels as our later chart will show.
The reduced operating frequency is likely to translate into a performance deficit for the Ryzen 7 5800X3D versus the 5800X in workloads that do not leverage the added L3 cache highly.