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DDR4 Memory Overclocking Report and Beginner's Guide

By: Steven Bassiri | Guides | Posted: Jan 6, 2015 1:10 pm

Test Setup




The setup here is pretty simple. If I had started testing two weeks prior to the date I started testing, then I would have had to use two motherboards, as the X99-SOC Force wasn't overclocking the 32GB Crucial kit over 2400MHz, and it wasn't able to get over 3250MHz on the memory. Over the last few weeks, the BIOS updates have made huge improvements to DDR4 overclocking on this motherboard. I used BIOS F6i for these tests because it provided the quickest DDR4 training, and as you will see soon enough, training is a key part to high-speed DDR4.




Sometimes you are stuck with using lower multipliers for the memory as stability, and ease of use is higher with the 1.25x divider on many boards. Don't be upset if your board doesn't boot above 26.66x, as this isn't your board makers' fault, it's just the slow progression of DDR4 code in the stock AMI UEFI code. This doesn't mean that you can't use higher speed kits, it just means you have to invoke the BCLK divider. As you can see in the image above, when you change the BCLK divider, it has an effect on almost all of the clock frequency domains (CPU, Uncore/Cache, and Memory). Don't forget to dial back the CPU and Uncore/Cache ratios; if you forget to lower the CPU and Uncore/Cache ratios, then you could face instability.




Timings, timings everywhere! DDR4 comes with a lot of timings, and if you just love to alter the timings to find the best one in the billions of possible combinations, then DDR4 will be fun for you. However, that isn't the point of this guide. In this guide, I will only deal with the primary timings CAS, tRCD, tRP, tRAS, and of course, CR (command rate). You might also be happy to know that Intel has brought back real-time timing changes in Windows! However, RTL (Round Trip Latency) and IOLs can't change after initial boot up and training, and consequently, some timings like CAS won't really make much difference to performance if they are changed in Windows.




DDR4 is pretty resilient; although default DDR4 voltage is 1.2v, I have run at 1.5v on-air many times without active memory cooling. All of my kits are still 100% alive and kicking; however, I am not recommending you do this. I would suggest staying under 1.4v for 24/7 usage. The memory controller in the CPU is based on the DDR3 controller, so higher voltage levels won't damage it either. The VPP voltage is okay to mess with at very high speeds; otherwise, it is pretty high at default. The only CPU voltage you need to change for memory overclocking is the VCCSA, or system agent voltage. I would say anywhere from +0.3v to +0.5v for very high overclocks is acceptable. Your board will probably auto increase VCCSA for you anyway, as most boards I have tested do increase VCCSA on "Auto".



The Kits




First up, we have the Crucial 32GB (8GBx4) 2133MHz Micron based kit. This is basically the go-to for anyone seeking a solid 32GB of DDR4 in only four sticks. We will find out later if the fact that it is double-sided has any impact on overall performance.




Next, we have this nice kit from ADATA, which is rated at 2400MHz, and offers a slight increase in speeds over the Crucial kit. However, this ADATA kit is only 16GB. This kit actually features the same type of Hynix memory as the G.Skill kit - just not as binned.




This is our high-speed G.Skill kit that we also use in our motherboard overclocking articles. G.Skill has this kit rated at 3200MHz, but it is also only 16GB. This kit produced our highest overclocks, and it's pretty easy to lower the timings, even at 3200MHz.




I took the heat sinks off, and not just to look at what's under the hood, but also for thermal tests later on in the article. Both the G.Skill and ADATA kits I have today are based on single sided SK Hynix.

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