First of all, measuring "Effective Clock" only works properly close to 100% load. Else it is a mess of real idle/C-states and HWiNFO putting even too much emphasis on C-states (compared to Ryzen Master's effective clocks). In the following screenshots positive Clock Reduction % means C-states, negative means clock reduction
below the global frequency limit
without C-states (but only relevant close to 100% load).
Curiously average (effective) clock-rates are always about 10-13 MHz below the global frequency limit when all logical cores are fully loaded by P95 (not so by CB23 or when P95 only loads a smaller number of cores).
Idle, C-states enabled, stock:
Idle, C-states disabled, stock:
P95, small FFT AVX, stock:
P95, small FFT AVX, PBO "Motherboard limits" + CO, slightly temp limited at 90°C:
CB23, PBO "Motherboard limits" + CO, not temp limited at 80°C:
P95, Small FFT AVX, PBO "Motherboard Limits" + CO, LLC Mode 8 (lowest on MSI), not temp limited at 83°C:
Statuscore, only EVEN cores, PBO "Motherboard Limits" + CO, LLC Mode 8, not temp limited at 77°C:
All clock-reductions are measurable as such in my example. As far as I can tell my CB23 tests results of various settings always corresponded close enough to the measured clocks that nothing hidden seems to have affected them outside of test variances. So either I need another testing method to reproduce performance drops without seeing measured global limit / effective clock-rate drops, or your performance drops should be measurable as global limit / effective clock-rate drops as well.
PS: "Motherboard limits" seems to mess with Scalar, too, else CB23 would not run at 4600 MHz and P95 would not pump over 230 W through my CPU. Even when I manually set it to x1 it hits that high, while I am pretty sure it did not do so before I specifically set it to x10 in former test-runs. Might have to recheck, but that's not really relevant for these screenshots.
PPS: "Core Power Average" should be labeled "Cores Power", as it is the sum of all specific cores' power consumption sensors (per CCD) put together in a custom sensor. I only noticed the wrong labels after taking the screenshots.