Tweaking for Speed

When it comes to overclocking, things get a little bit complicated trying to understand all the technical terms and how they fit together. With the new AM5 socket, AMD has switched to DDR5 exclusively, leaving DDR4 behind. Those familiar with the ideal configuration from the previous platform can still apply some of the same overclocking principles here as well. Those new to the memory overclocking scene or need a refresher only need to follow a few rules to get started.

First is a quick refresher for AMD and DDR4. The ideal configuration for Zen 2 (3000 series) and Zen 3 (5000 series) based processors will always be to match the internal Infinity Fabric (IF) to the memory controller, which matches the frequency of the system memory as well. This is often referred to as a 1:1:1 configuration. Once the system memory exceeds the capabilities of the memory controller, a secondary system is in place to allow the memory to still function and operate by breaking this ratio. In doing so, the memory controller frequency is now cut in half, operating in a 2:1 configuration. This introduces a major latency penalty that negatively effects games that are memory sensitive with a measurable frame rate loss in some instances. AMD marketing uses DDR4-3600 as the "sweet spot" for Ryzen 3000 series, with DDR4-3800 best suiting Ryzen 5000 series processors. This is where cost vs. performance intersects, giving good results by using just X.M.P (A-XMP, DOCP, EOCP) DDR4-3600 profile and the motherboards auto settings. For the most part, this is a set and forget type of situation using single or dual-rank memory in the system for a total of two DIMMs. In the example above, DDR4-3600 in a 1:1:1 configuration would be 1800 MHz for all three. Generally speaking, ignoring outliers, 2000 MHz IF and DDR4-4000 RAM is the upper limit for this ratio when using an AMD Ryzen 5000 processor.

With the basics out of the way, we can talk about DDR5 and what to expect now that this new AMD (AM5) platform uses it exclusively. The AMD engineering team has changed the formula slightly from the ideal DDR4 configuration. The new "sweet spot" is now DDR5-6000 but with a twist. The Infinity Fabric (FCLK) is now independent and no longer is required to match the system memory for best results. In many instances a FCLK of 2000 MHz is the default value with a range "up to" 2133 MHz. It is highly suggested to leave this value at 2000 MHz, as higher frequencies often will outright refuse to work with a system hard-lock, requiring clearing the CMOS to recover. Even though some motherboard manufacturers have cited 2133 MHz as a possibility in media review guides, it may not be until the next CPU generation when we achieve these numbers consistently, without the aid of binned CPUs.

During the testing phase of different AMD motherboards and observation while working on these reviews, it seems that for now DDR5-6400 and beyond will be out of reach for many users. AMD AGESA / BIOS updates have already increased compatibility, but it isn't perfect. The standard setup of a 2:1:1 ratio works seamlessly through DDR5-6000. While a wide range of AM5 B650 / X670 motherboards support DDR5-6400+, this frequency and above can be problematic. Often lowering the FCLK and / or changing the memory ratio to 2:2:1 (Gear 2) will help alleviate some configurations that are struggling to get stable, like four single rank DIMMs at DDR5-6200, but this may not help to stabilize DDR5-6400 and above.

Caution is advised with DRAM voltage over the rated EXPO / XMP profile. Direct airflow or a waterblock may be necessary for long-term stability. This extends to the CPU as well. Raising the integrated memory controller voltage above AMD specifications may cause irreparable damage. Please proceed with care and do research before attempting this. Do not copy and paste values without understanding the impact first, especially if simply taken from screenshots posted on Discord or Reddit.


For thermal testing, Karhu stress test software was used for 30 minutes, after which both DIMM temperatures from the SPD hub sensors are averaged together. Testing was performed with and without a fan at the EXPO Profile of 1.40 V. DDR5 SK Hynix memory ICs are susceptible to temperature related system errors. Since more voltage is necessary for higher frequency memory, caution is advised when overclocking without a fan directly placed on the memory, or at least good case airflow. Otherwise, unexpected stability issues may occur as the memory warms up.

55°C is perfectly acceptable and will not be a problem. Introduce any amount of airflow to lower the temperatures.

AMD Results

HWBOT: Submission Link

Overclocking on AMD new platform is a challenge and can often lead to frustration with many system lockups, resulting in failed system boots that require clearing the CMOS to get out of the bind. AMD also has a fairly hard boundary limit of DDR5-6400 currently. Unfortunately, blaming the CPU memory controller is not the whole story here, because changing the gear ratio (2), does not solve the problem. This topic needs more time to be properly investigated, but generally DDR5-6200 is going to be the limit for most systems currently using auto EXPO / XMP settings. This value may increase with future BIOS updates, or it may not change at all until the next AMD processor series is released.

Being that this kit is using SK Hynix memory, a quick overclock and DDR5-7000 was achieved with a voltage of 1.5 using an Intel 13900K. Since this memory only has a EXPO profile, more overclocking was not pursued as this memory is marketed for AMD Systems, even though it does in fact work with Intel. Even if the EXPO profiles are not supported, you can always manually type in the settings. Switching back to AMD and sticking with the EXPO profile of DDR5-6000, Primary and secondary timings were adjusted for a slight improvement. Lowering the tFAW and tRFC values further would result in a system lockup requiring a Clear CMOS to get unstuck. This is unrelated to the memory and more due to early growing pains that are just part of learning the quirks of AMD new platform.

Note: All memory overclocks passed Karhu stress test 2000% or more.





Overclocking does provide a slight advantage over the EXPO profile. Being that this kit is already well binned, there is very little reason to overclock unless you are fully dedicated to the process, as improvements overall are quite low. That's not a bad thing. It just means Corsair already has a great pre-binned memory kit.