Intel DRAM Odd Ratio Mode enables the use of odd (as in: not even) DRAM memory multipliers which enables more fine-grain memory overclocking.
The Odd Ratio Mode feature was first introduced with the Skylake processors in August 2015 and was later removed with the Rocket Lake processors in March 2022.
When Odd Ratio Mode is enabled, the DRAM memory multiplier is offset by 1 step of either 100 MHz or 133 MHz frequency. This enables even more fine grain memory overclocking. Furthermore, it further removes the reliance on BCLK overclocking to achieve specific memory frequencies.
You can find an example in below table.
With Odd Ratio Mode is enabled, the maximum supported memory frequency was
- DDR4-4133 for Skylake processors (133 MHz x (15×2+1))
- DDR4-4133 for Kaby Lake processors (133 MHz x (15×2+1))
- DDR4-5500 for Coffee Lake processors (100 MHz x (27×2+1))
- DDR4-5500 for Comet Lake processors (100 MHz x (27×2+1))