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 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.



The E-Core side of this chart (threads 17 to 32) can be somewhat misleading. It looks like the cores run at increasingly slower frequencies as the load goes up, but that's not the case. The frequency plotted is the average of all the P-Cores active, plus more and more E-Cores, which all run at a lower frequency than the P-Cores, which drags down the average.

That's why I tested E-Core frequency scaling separately in the chart below.



The E-Cores always run at 4.3 GHz, no matter how many of them are loaded.

Overclocking

Overclocking the Core i9-13900K is easy, thanks to its unlocked multiplier. The biggest problem is the heat though, even at stock you'll be reaching 100°C and higher. Overclocking the 13900K means setting thermal limit to 115°C up from 100°C, and then figure out what's the highest voltage you can give the CPU without hitting throttling at 115°C, depending on your cooling solution. Switching from air to our Arctic AIO helped with controlling the heat, but it wasn't a huge difference. Our maximum all-core OC is 5.6 GHz on the P-Cores, plus 4.4 GHz on the E-Cores, 100% stable. this still isn't enough to beat the stock configuration in lighter applications, because here the CPU will boost two cores up to 5.8 GHz.