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: I used the XMP profile and increased the frequency until the system lost stability. After finding that limit, I manually tweaked for the maximum frequency and lowest possible timings. Voltage modification from stock is allowed. After all, this is overclocking!

The 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 with the CPU memory controller, or in a 2:1 ratio. With the release of Intel's 12th Gen Alder Lake based processors came DDR5 support and the additional 4:1 ratio.

1:1 ratio generally falls between 3600 and 4000 MT/s for Alder Lake CPUs. This is completely dependent on the CPU memory controller and supporting voltages. In rare instances, higher-end motherboards can increase this slightly and offer better overall compatibility due to trace length, PCB layer count and better memory training algorithm. My Intel Core i9-12900K maxes out at DDR4 4133 MT/s, which is rare if going by the sheer number of forum posts about many struggling to reach 3800 MT/s. It is safe to say that anything greater than 3600 MT/s in a 1:1 ratio will require a bit of hands-on tuning.

Since DDR5 has a higher operating frequency and dual 32-bit data bus, synchronously operating it in 1:1 is unlikely to function at all. That only leaves 2:1 Ratio and above as a viable option for any DDR5-based setup. 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 set this in the BIOS. With this information, Intel 12th Gen Alder Lake paired with DDR5 will gain 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 4:1 ratio being beneficial to only certain applications that need the increased overall bandwidth DDR5-8000+ can provide.

Those looking to overclock will generally find a hard barrier around 6600 MT/s using the Intel Z690, as many 4-slot motherboards do not support higher speeds. Only a handful of motherboards are designed to support 6666 MT/s and up. These are the ASUS Z690 Apex, Gigabyte Z690 Tachyon, MSI Z690 Unify-X, ASRock Z690 AQUA OC, and EVGA Z690 Dark.

Caution is advised with 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 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 sensor are averaged together. Testing was preformed with and without a fan at the XMP of 1.4 V and an overclocking voltage of 1.5 V. DDR5 SK Hynix memory ICs are susceptible to temperature related system errors as well. Since more voltage is necessary for higher frequency memory, I caution against 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.

That being said, this Corsair Dominator Platinum RGB kit did exceptionally well without any airflow and the only memory kit I have tested so far to pass the 1.5 V stress without producing errors during the no airflow portion.

Intel Results

Following in the footsteps of the previous memory review, I used the same frequencies and timings to start off and adjusted accordingly. Using the overclocking-orientated Gigabyte Z690 Tachyon, we start the overclocking sessions with a minor boost to the voltage. With 1.45 V, 6800 MT/s was obtainable along with similar timings to the base XMP profile. These primary, secondary and tertiary timings of course can be lowered even further. However, that will be completely dependent on the IC quality in each memory kit and the amount of voltage one is willing to apply.

The next step was to raise the voltage a bit more and enter the elite enthusiast realm where only a handful of Intel Z690 based motherboards can properly run 6933 MT/s+ memory. Corsair Dominator Platinum RGB was easy to tame. Generally a bit back and forth with timings and voltage is required to narrow in on stability at this frequency. Here however, it was fairly easy and sped up by loading a previously saved profile. It surprisingly passed stability tests on the first go.

While no set overclock is ever guaranteed, having a pre-binned kit helps things along tremendously. Given how well DDR5-6933 overclocking went, some time was spent with 7000 MT/s, but ended without being fully stable. The DDR5-7000 barrier can be viewed as a mixture of not enough DRAM voltage paired with borderline unsafe adjustments to the System Agent (SA), vDD2 (memory controller), and TX VDDQ voltages as well. These CPU related voltages will vary based on the motherboard, as well as some memory timings. I have confidence that this kit can accomplish full stability at DDR5-7000, but it is far from a plug and play type operation.

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




Given how close these memory profiles scored, unless more time is spent adjusting the sub-timings, light overclocking is not recommended here. Given that the XMP profile of 6600 MT/s is the least problematic of the bunch and already gives great results, this is a win-win. No reason to spend time of further tuning unless this is part of your hobby.