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 the 1:1 ratio intact. This is slightly lower than 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 one available is important as stability issues are still being ironed out.

The Neo Forza Faye DDR4-5000 breaks the 1:1 ratio because of the high operating frequency. Once 2:1 is enabled, the goal is the go as high as possible with the lowest-possible timings. As this is running at 5000 MT/s, manual adjustments in the BIOS are required for the best results.

Intel Results

With the Intel Core i9-11900K, I was able to achieve 2666 MHz, which is a new personal DDR4 record for me. It did require swapping over to the Gigabyte Z590 Xtreme as the MSI Z590 ACE had a difficult time just with the XMP profile. The downside with such a high operating frequency is the abusive amount of voltage required for both the system agent (SA) and VCCIO2 (IMC); 1.55 V and 1.6 V respectively. Long-term use with those voltages applied will certainly degrade the 11th Gen Intel CPU and is not recommended.

Being that up is not always better, I ventured down to 3600 MT/s while keeping the 1:1 ratio. After tightening up the timings a bit, It turns out to be a well-binned kit. Hynix ICs will never be able to match Samsung B-Die in terms of lowest latency, but is often cheaper to purchase. These also have the privilege of officially operating at 1.6 V without voiding any warranty.

AMD Results

For AMD, I decided not to venture higher as it just isn't beneficial outside of select benchmarks. Because the AMD test system consists of a Ryzen 7 5800X, the best configuration is actually DDR4-4000 with a FCLK of 2000 MHz instead of the highest-possible frequency. Not all Zen 3-based CPUs can achieve this, though. A fallback of 1900 MHz is acceptable as well. Both tests did well respectively. A CAS value of 14 is reserved for Samsung B-Die. For SK Hynix DJR ICs, CL16 is nearing the lowest-possible value it can achieve under normal circumstances.