Base Clock and DDR speed interaction

Q.: I've been asked why the DDR memory speed in CoreFreq isn't as accurate as the RAM specified value ?

A.: The reason is that the specified speed is weighted by the estimated base clock frequency (BCLK).

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• Let's start in BIOS with a default base clock of 100 MHz and a DDR speed rated at 3600 MT/s

• Now I'm slightly raising the BCLK from 100 MHz to 100.8750 MHz

  As shown in the below screenshot, you observe an overclocking of the Target CPU speed but also a Memory frequency increased to 3631 MT/s

• Let's run CoreFreq to check its estimation of the frequencies:

  You can read here a Memory Controller Bus Rate of 1800 MHz (the specs value), weighted by a Base Clock of 100.866 MHz which computes a Bus Speed of 1815 MHz and thus a DDR Speed of 3631 MT/s.

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To conclude CoreFreq is designed to match as its best the BIOS clock frequencies.

Tips

• If your DDR speed is not actually what you were expected then have a look in the BIOS for the "Spread Spectrum" options to disable them.
  As result you should get a pure 100 MHz Base Clock.
• Various BIOS performance settings may also alter the BCLK on your behalf. Disable them or set them to a standard value as specified by the Processor manufacturer.