Clock Frequencies

The following chart shows how well the processor sustains its clock frequency and which boost clock speeds are achieved at various thread counts. This test uses a custom-coded application that mimics real-life performance—it is not a stress test like Prime95. Modern processors change their clocking behavior depending on the type of load, which is why we provide three plots with classic floating point math, SSE SIMD code, and the modern AVX vector instructions. Each of the three test runs calculates the same result using the same algorithm, just with a different CPU instruction set.

CCD Clock Speed Mismatch

During testing I noticed that the second CCD on my 7950X clocks its cores considerably lower than the first CCD.

[Adding pics for 7900x soon, the 7950x review has those already]

I reached out to AMD and haven't received a response yet. Once I do, I'll update this review.

Overclocking

The Ryzen 9 7900X comes with a fully unlocked multiplier, which makes multiplier-based all-core overclocking very easy. I dialed the voltage up to 1.32 V, which is about the maximum I could run Prime95 at and not overheat by crossing 115°C—even with a powerful AIO. Using Arctic's AIO with "Ryzen offset mounting" helped shave a few degrees off the CPU temperature. At this voltage, with Prime95 running, I kept increasing the multiplier in Ryzen Master until the system became unstable. There was no way that 5.3 GHz all-core would be fully stable, so I settled for 5.2 GHz. You might see some higher overclocks in other reviews, unless these had really good silicon, and/or were paired with exceptional custom watercooling or dry ice/LN2, there's no way these were verified to be stable with Prime95 and only lighter tests were run. Just to clarify, the limit here is not the OC ability/voltage, but the CPU temperature, which limits the voltage you can use.