Tweaking for Speed

With testing out of the way, I endeavored to see if these sticks have any headroom. For Intel, I kept the same procedure I have been using, leaving all settings at their XMP defaults and then increasing the frequency until the system loses stability. After finding that limit, I manually tweaked for the maximum frequency. Voltage modification from stock is allowed. After all, this is overclocking!

A good starting point for Ryzen Zen 3 based builds is 3600–4000 MT/s, as it is optimal because of the Infinity Fabric limitations. For those unaware, AMD Ryzen CPUs can in some applications benefit substantially from a synchronized 1:1 ratio with the system memory and Infinity Fabric. This extends to the Ryzen 3000 series as well, though with it topping off around 1900 MHz instead to keep 1:1 ratio intact. This is a bit lower compared to the Ryzen 5000 series, but still preferred over the 2:1 ratio configuration.

On the Intel side of things, 8th to 10th Generation Intel Core processors are going to benefit the most from the highest-possible frequency with the lowest timings. That being said, 3733–4000 MT/s is the ideal target range since there is no need to play around with VCCSA/IO voltages, and it is mostly plug and play. Switch to an 11th Gen Intel Core processor and things change given the introduction of the memory controller Gear ratio similar to what AMD has done. Once you surpass the memory controller's ability to stay in synchronous 1:1 mode, most motherboards will automatically switch to 2:1 ratio. If all else fails, you can manually set this in the BIOS.

For the 11th Gen Intel Core i9-11900K used in this test system, 1:1 ratio stops at a messy DDR4 3600. No matter the VCCSA/IO voltage or memory kit I use, this is the limit for this CPU. Any higher and I must switch to 2:1. Some have reported upwards of 4000 MT/s 1:1 support, but I am not one of the lucky few.

With the release of Intel's 12th Gen Intel Core processors, not much has changed from the fundamentals introduced in the previous 11th generation. However, the biggest change here is the i9-12900K CPU. With a bit of IMC voltage tuning, it can reach 4000 MT/s while keeping the 1:1 ratio to the memory controller. Updating the BIOS to the newest available version is important as stability issues are still being ironed out.

The XPG SPECTRIX D50 ROG CERTIFIED RGB using the XMP profile of 3600 MT/s is great for Intel and AMD alike. Not only is it ideal for the AMD Ryzen 3000 and 5000 series, it benefits Intel 11th and 12th Gen as well. This is all owing to the 1:1 ratio being achievable on both platforms without diving into the BIOS settings or voltages. Most motherboards should have no issues with the provided XMP profile. If you are unlucky and have a weak CPU memory controller or low-end motherboard, manually changing the Command Rate from 1T to 2T may solve any lingering problems.

Intel Results

With the Intel Core i9-11900K, I was able to achieve 2000 MHz with all other XMP settings at their default, which is great. It shows that XPG binned this kit well, and it has some headroom. Unfortunately, this memory overclock is less appealing because the break from 1:1 ratio increases latency.

The next step was to go as high as possible. Swapping to the Gigabytes Z590 Xrtreme, I was able to achieve 5000 MT/s with 1.6 V applied. This was the soft-limit of the memory. Hynix DJR ICs can handle 1.7 V with proper cooling, but 5333 MT/s isn't a great return considering the voltage and additional tweaking.

AMD Results

For AMD, the best results are generally to keep it within the FCLK 1:1 ratio. Using the XMP profile, I was able to reach 4000 MT/s without any
additional adjustments. Applying more voltage allowed the CAS value to be lowed to 16. This is generally considered the lowest value Hynix DJR can achieve. Since this required 1.5 V, some adjustments to tRFC and tFAW were made to get even better results. The rest of the primary values could not be lowered without inducing errors.