Had an 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 platform and an 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.
Intel Results
DDR5-8200 Submission Link
After all the main benchmarks were completed, it was time to start the overclocking portion of this review. While CPU-Z revealed this memory kit was SK Hynix based memory, it does not say the revision. Given that these are the new 3 GB ICs, a lot is still unknown as to what the maximum operating voltage is for long term use. Taking the heatspreader off gave that part the needed number: H5CGD8MHBD-X021. This is the first 3 GB revision from SK Hynix with the denotation - M-Die, not to be confused with the 2 GB M-Die. In any case, a personal DRAM voltage limit of 1.5 was set for daily use, which is more than enough for a nice overclock.
To start off, the values of the G.SKILL DDR5-8000 48 GB memory kit were copied (40-48-48-128). Surprisingly, it booted and was completely stable during the stress tests. Lowing the CAS value at all caused a none-boot. The next step was to max out this CPU, which is 8200 MT/s with safe daily voltages. A bump to 1.4 V (DRAM) for it to boot (40-52-52-131) and eventually errored out in the memory stress test after an hour. Raising this to 1.45 V, solved that, but the timings still could not be lowered without a none-boot scenario. Raising the DRAM voltage to 1.5 V allowed for small adjustments to the primary and sub-timings, but didn't quite catch up to SK Hynix A-Die (2 GB).
Those who are looking to just stick with 7200 MT/s and just optimize the timings, will be disappointed to find these new 3 GB ICs, do not scale down well (even with voltage). They do much better going up in frequency.
Using the XMP 7200 MT/s profile as a baseline, we can see how much extra performance just 8000 MT/s can provide. 8200 MT/s with all the tweaks edges out ever so slightly, but the time it takes to dial in the settings may not be worth it. As always, it's important to point out that no overclock is ever guaranteed, which makes memory overclocking a new adventure every single time. This also means that the same settings may require more voltage for a different kit or may not be possible at all depending on the motherboard, CPU and how well the memory performs beyond the rated XMP profile.