Clock Frequencies

The following chart shows how well the processor is able to sustain its clock frequency, and what boost clock speeds are achieved at various thread counts. This test uses a custom-coded application that mimics real-life performance (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.

Overclocking

As mentioned before, the Core i5-10400F has its multiplier locked because it lacks the "K" suffix, which means you can't just set any desired CPU frequency.

Just like on previous Intel CPUs it is possible to increase the BCLK frequency above its default of 100 MHz on most motherboards. This results in a higher total CPU frequency, as BCLK x Multiplier = CPU Frequency.

With Comet Lake, and Z490 specifically, Intel marketing has made some noise about the new ability to independently adjust BCLK from PCIe clock. In reality, this doesn't do anything for non-K processors because all locked CPUs will measure the BCLK they are running at and simply refuse booting if BCLK is 103 MHz or higher.

That's why our maximum overclock is with the BCLK at 102.9 MHz. The measurement isn't 100% precise, so with "102.99" set in the BIOS, you'll often end up with a hang at POST even though the frequency is technically lower than 103 MHz.

We also increased the power limits for our "Max Turbo" and "Max Turbo + 103 BCLK" runs. By default the limits are PL1 = 65 W and PL2 = 134 W; we increased that to the maximum for these two tests, which yields a little bit of extra performance, but not enough to invest in a more expensive motherboard.