Had a Overclocking Dream Lately?
Overclocking Tips and Tricks
Spoiler: Intel DDR5 Tweaking
With testing out of the way, it is time to see if this memory kit has any additional headroom. For Intel, we start off by using the XMP profile and increasing the frequency until the loss of system stability. After finding what can be accomplished without changing any of the timings or voltage, the second step can begin. This is where we go for the maximum frequency and lowest possible timings. Voltage modification above the XMP profile is allowed. After all, this is overclocking!
Intel's 11th Gen Intel Core processor paved the way for things to come. The introduction of the memory controller Gear Ratio allowed the system memory to run in synchronous 1:1 mode (Gear 1) with the CPU memory controller, or in a 2:1 ratio (Gear 2). With the release of Intel's 12th Gen Alder Lake based processors came DDR5 support and the additional 4:1 ratio (Gear 4).
It is generally considered that between 3600 and 4000 MT/s is the upper limit for Gear 1 support when using a Alder Lake (12th Gen Intel) CPU. This of course is partially dependent on the CPU memory controller and supporting voltages related to memory. In rare instances, higher-end motherboards can increase this slightly and offer better overall compatibility due to shorter trace length, higher PCB layer count and a better memory training algorithm. For instance the Intel Core i9-12900K used for these memory reviews maxes out at DDR4 4133 MT/s for single-rank memory. Achieving 4133 MT/s is quite a unlikely occurrence judging based by the sheer number of forum posts of many users struggling to get 3800 MT/s stabilized. It is safe to say that anything greater than 3600 MT/s using Gear 1 will often require a bit of hands-on tuning.
Since DDR5 has a higher operating frequency and a dual 32-bit data bus, synchronously operating it in 1:1 does not function at all. So far there have been no confirmed reports of this working for DDR5. That only leaves 2:1 Ratio and above as a viable option for any DDR5-based setups. The motherboard should automatically switch to the 2:1 ratio for both DDR4 and DDR5 above 3600 MT/s. If all else fails, you can manually enforce Gear ratios in the BIOS as well. With this information on hand, we can deduce that Intel 12th generation processors using DDR5 in theory will benefit the most from the highest-possible frequency, until the 2:1 ratio is not longer possible. At that point the cycle starts over again with a new 4:1 ratio and even higher frequency system memory.
Those looking to overclock on a Intel platform will generally find a hard barrier around 6600 MT/s using the Intel Z690 and Intel 12th Gen CPU. Switching to Intel 13th Gen, this value increases to 6800-7200 MT/s when using Intel Z690 motherboards and 7800-8000 MT/s for Intel Z790 4-slot motherboards. Special overclocking specific motherboards like ASUS Z690 Apex, Gigabyte Z690 Tachyon, MSI Z690 Unify-X, ASRock Z690 AQUA OC, and EVGA Z690 Dark can reach up to DDR5-8000+. While the new wave of Z790 versions start at DDR5-8000 and can reach up DDR5-9000+ with exotic cooling such as LN2.
Caution is advised when raising DRAM voltage over the rated 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 (VDD2), System Agent (SA), and VDDQ_TX above Intel 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.
Getting Warm?
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 XMP Profile of 1.40 V. DDR5 SK Hynix memory ICs is susceptible to temperature related system errors. Since more voltage is necessary for higher frequency memory, caution is advised when overclocking without direct airflow across the memory, or at least decent case airflow. Otherwise, unexpected stability issues may occur as the memory warms up.
Hynix A-Die needs to stay below 50°C when pushing past 7600 MT/s~. Overclocking memory to DDR5-8000 errors out around 45°C for a reference point. Tighter sub-timings and longer cell refresh cycle errors will greatly depend on the memory temperature as well. This is why retail kits generally have looser timings to account for different operational environments.
Intel Results
DDR5-6800 Tight Timings Submission Link
DDR5-7800 Submission Link
DDR5-8000 Submission Link
Where to begin... For starters SK Hynix A-Die is a monster when it comes to scaling up. This kit isn't binned beyond 6800 MT/s, yet for short durations from a cold boot, 8000 MT/s worked. Generally that was short lived as once the memory warmed up a bit, it started failing y-cruncher 2.5B benchmark. After some investigation one of the two DIMMs just wasn't good enough after individually testing each separately. The next step was to validate the highest sustainable overclock using both DIMMs. 7800 MT/s had similar problems with the tighter timings, but the duration before system errors was about 10 minutes. Loosening up the primary timings solved this. By doing so, it defeated the purpose of a high frequency memory kit, as now it wasn't any better compared to a lower frequency tuned kit because of the latency increase.
The next overclocking adventure was to stick with 6800 MT/s and drop the primary timings as low as they could go, along with adjustments to many of the secondaries. It doesn't quite match what Hynix M-Die could do, but the results did provide a slight performance increase over the XMP profile none the less. A direct fan on the memory was required for both overclocks to keep it below 50°C. Such is the nature of overclocking beyond the retail XMP profile.
Note: All memory overclocks passed Karhu stress test 2000% or more.
Overclocking this memory kit was a fun adventure, but it has limited benefits outside of just benchmarks. No matter, while the RTX 3080 Ti is the limiting factor for the games, DDR5-7800 isn't a simple set and go setup and no overclock is ever guaranteed. A fan placed on the memory is required for this overclock as system errors are not uncommon, stability issues will occur if the memory gets too hot.