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Overclocking Tips and Tricks
Spoiler: AMD DDR5 Tweaking
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 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 from observation while working on these reviews, it seems that for now DDR5-6400 and beyond will be out of reach for many users in a memory ratio of 1:1. AMD AGESA / BIOS updates have increased compatibility. The standard setup of a 2000 MHz 1:1 ratio works well through DDR5-6000. While a wide range of AM5 B650 / X670 motherboards support DDR5-6400+, this frequency and above can be problematic without some manual intervention for motherboard settings. Often lowering the FCLK and / or changing the memory ratio to 2:1 (Gear 2) will help alleviate some configurations that are struggling to get fully stable.
Caution is advised with raising DRAM voltage over the rated EXPO / XMP profile. Direct airflow 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.
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Unless you have a 2-slot motherboard, to maximize that 2:1 memory ratio targeting DDR5-8000 becomes completely out of reach for Ryzen 7000 series. Instead, for a majority of users, getting the most out of AMD is about tweaking the primary and sub-timings paired with the highest memory frequency while still maintaining that 1:1 memory ratio to the CPU IMC. Memory tweaking on AMD is also especially challenging for beginners, with many system lockups. Simple things like going too low on the tRFC value will prevent a boot even into the BIOS, which now requires clearing the CMOS to get out of the bind.
With that said, the AMD Ryzen 7000 CPUs has a fairly hard boundary limit of DDR5-6600. The good news is that with the AGESA 1.0.7.0 BIOS update and beyond, it has become easier to reach DDR5-6400, even with the SoC voltage restriction now in place.
In any case, Corsair already provided a good starting point with its DDR5-6200 (OC) profile. While not officially supported (binned), it is included nonetheless. Chances are it will work if the CPU IMC is strong enough to handle it. Instead of manually entering all the timings and voltages, enabling this profile is much easier for the end user. But we aren't done here. After validating that the DDR5-6200 EXPO profile worked, a few extra adjustments happened. Firstly, Infinity Fabric was raised to 2066 MHz to keep in step and secondly, tRAS, tFAW, tRFC (2) values helped speed things along.
Absolutely more could have been done to the secondary timings, but at a certain point it comes down to the motherboard and CPU combination, which doesn't apply to every system either. This was a happy medium reached and more plausible to achieve with most of the time invested in the validation of stability.