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.



Now let's see what happens when we lift the chip's power limit from 65 W to the maximum.



Suddenly, the chip runs A LOT higher frequencies, especially with multiple cores active.

Overclocking

As mentioned before, the Core i5-11400F 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 the BCLK through the PCIe clock. This option is available on Z590, too, but in reality, it doesn't do anything for non-K processors because all locked CPUs will measure the BCLK they are running at to simply refuse booting if BCLK is 103 MHz or higher.

That's why our maximum overclock is with 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.

Increasing BCLK also increases memory clocks accordingly, which puts more stress on the memory controller. Unfortunately even that small increase ran the memory controller at too high a clock (1866 MHz to 1923 MHz), so I had the choice to go with Gear 2 or settle for the next-lowest memory frequency setting, which is 1800 MHz x 1.03 = 1854 MHz = DDR4-3700 and close enough to our DDR4-3733 baseline for the other tests.

On a side note, if you are using XMP timings with Gear 2, make sure "1T" timing mode is set in BIOS. Since Gear 2 halves the memory controller frequency, a delay of 1T becomes 2T at Gear 1. So if your XMP profile specifies the "2T" command rate, setting 2T with Gear 2 would actually result in 4T.