AMD Ryzen - Single-Rank Versus Dual-Rank DDR4 Memory Performance

After finishing up our DDR4 memory scaling article on an AMD Ryzen processor with an AMD X370 chipset powered board we were left wondering if memory performance and scaling was similar on different AMX X370 motherboards from different manufacturers. We gathered up the MSI X370 XPOWER GAMING TITANIUM ($299.99), GIGABYTE GA-AX370-Gaming 5 ($194.99) and ASUS ROG Crosshair VI Hero ($254.99) motherboards as the three boards that we were going to try out. Looking at the 'big 3' motherboard markers should give us a pretty good idea if there are any big differences to be had on memory. When it comes to the memory kits we wanted to test with just two and then all four DIMM slots populated and we also needed to test with single-rank and dual-rank memory modules. Knowing that Samsung Rev B memory IC's are said to do well on this platform we turned to Corsair Vengeance LPX memory kits and ended up getting the Corsair Vengeance LPX 64GB (4x16GB) DDR4 3600MHz C18 ($669.99) for dual-rank testing and the Corsair Vengeance LPX 32GB (4x8GB) DDR4 4000MHz C19 memory kit ($504.99) for single-rank testing. Both of these kits are overkill for the AMD X370 platform, but we'll also use them down the road for testing on Intel platforms and hopefully Ryzen again if any performance improvements are ever unlocked. [caption id="attachment_192972" align="aligncenter" width="645"]AMD Ryzen X370 Motherboards and Corsair Vengeance LPX DDR4 Memory Kits What $1,925 Worth of AMD X370 Boards and Corsair DDR4 DRAM Look Like![/caption] So, we'll test each of the three boards at 2133MHz, 2400MHz, 2666MHz, 2933MHz and 3200MHz DDR4 memory settings with the single-rank kit in 2-DIMM and 4-DIMM configurations and then again with the dual-rank configuration in 2-DIMM and 4-DIMM configurations. Easy right? Actually, that adds up to being 60 different testing configurations if we can hit those speeds for on each board. Times that by 3 and you'll end up with a couple hundred data points per benchmark. Since, we've already tested a handful of benchmarks in our Ryzen DDR4 memory scaling article we'll just be using AIDA64 this time around to catch any big differences between the boards. Official Ryzen DDR4 Memory Support Officially, AMD Ryzen platforms support the following memory configurations: The good news is that we were able to exceed all of AMD's specifications for Ryzen memory! Let's take a look and see what we were able to come up with.

AMD Ryzen 7 1700 Test Platform

AMD Ryzen Test System The AMD AM4 platform that we used to test the Ryzen 7 1700 was run on the following boards and UEFI versions: You can see the HWiNFO64 details for each platform below: [gallery ids="192980,192981,192982"] The processor was run at stock settings. The Corsair Vengeance LPX DDR4 memory kits were run at 14-14-14-28 memory timings at all clock speeds. We used an NVIDIA GeForce GTX 1080 8GB Founders Edition with GeForce 378.78 WHQL drivers. We also used the Corsair AX860i digital power supply, Corsair Hydro Series H110i water cooler and Corsair Force MP500 480GB PCIe SSD on the system.
AMD AM4 Test Platform

Component

Brand/Model

Live Pricing

Processor

AMD Ryzen 7 1700

Motherboard

MSI X370 XPower Titanium Click Here

Memory

16GB Vengeance 3000MHz DDR4 Click Here

Video Card

GeForce GTX 1080 Ti FE Click Here

Hard Drive

Corsair MP500 480GB Click Here

Cooling

Corsair H110i Click Here

Keyboard

Corsair K70 RGB Click Here

Mouse

Corsair M65 Pro Click Here

Power Supply

Corsair AX860i Click Here

Monitor

ASUS PB287Q 4K Click Here

Operating System

Windows 10 64-Bit Click Here
It should also be noted that we used AIDA64 Engineer Build 4103 for the memory benchmarking application.

Dual-Rank DDR4 Memory Performance on AMD Ryzen

For dual-rank testing we went with the Corsair Vengeance LPX 64GB (4x16GB) DDR4 3600MHz C18 memory kit that is sold under part number CMK64GX4M4B3600C18. This 64GB memory kit runs $702.99 shipped on Amazon or $669.99 shipped over at Newegg. This is one expensive memory kit, but we if you are looking to run 64GB of high-end DDR4 memory and only have four DIMM slots available you don't have too many inexpensive options. Our particular kit was a version 4.31 model that uses Samsung Revision B DDR4 memory IC's on it. Corsair Vengeance LPX DDR4 3600MHz 32GB Kit We used this kit on the MSI X370 XPOWER GAMING TITANIUM, GIGABYTE GA-AX370-Gaming 5 and ASUS ROG Crosshair VI Hero motherboards and found that we could only run it at 2133MHz, 2400MHz and 2666MHz on each of these three AMD X370 boards. When we tried to run the 2933MHz memory strap each of these three boards failed to successfully boot and we never made it to the Windows 10 load screen. Please note that differences between the boards is very small, so rather than starting the Y-Axis at zero and showing one solid line we started the lower axis higher to have prettier charts. AMD Ryzen Dual-Rank Memory Performance One thing that we noticed when doing our memory performance testing is that AMD has a bug in their code. When using dual-rank modules or populating all 4 DIMM slots it should force you to use the 2T command rate. There is a bug in the latest uCode that lets you run at 1T command rate just on the 2666MHz memory strap. This is one of the reasons the performance jumps up so much when moving from 2400MHz to 2666MHz. We've let AMD know about the 'bug' and told them they should just allow end users to set the command rate manually as obviously 1T command rates can be run and there are big gains to be had. We start to see some differentian between boards when looking at the write memory bandwidth and the ASUS ROG Crosshair VI Hero motherboard does pretty well across the these three speeds with both 2 and 4 DIMM slots populated. AMD Ryzen Dual-Rank DDR4 Memory Latency Performance When it comes to memory latency all of the boards are close and you can see that running 4 DIMMs will give you a higher latency than just 2 DIMMs.

Single-Rank DDR4 Memory Performance on AMD Ryzen

For single-rank testing we went with the Corsair Vengeance LPX 32GB (4x8GB) DDR4 4000MHz C19 memory kit that is sold under part number CMK32GX4M4B4000C19. This 64GB memory kit runs $504.99 plus shipping and is only available direct from Corsair for the time being. Our particular kit was a version 4.31 model that uses Samsung Revision B DDR4 memory IC's on it. Corsair Vengeance LPX DDR4 4000MHz 32GB Kit We used this kit on the MSI X370 XPOWER GAMING TITANIUM, GIGABYTE GA-AX370-Gaming 5 and ASUS ROG Crosshair VI Hero motherboards and found that we could run it at 2133 to 3200 MHz without any issue on each of these three AMD X370 boards with tighter CL14 timings when 2 DIMM slots were populated. With all 4 DIMM slots populated with sided modules we were only able to get up to 2666MHz. Please note that differences between the boards is very small, so rather than starting the Y-Axis at 0 and showing one solid line we started the lower axis higher to have prettier charts. AMD Ryzen Single-Rank Memory Performance 2 DIMM single-rank performance looks good as all the boards use a 1T command rate at all times, so it was generally higher than the same board running with all 4 DIMM slots occupied. The 4 DIMM performance numbers are a little confusing as at 2133MHz and 2400MHz the boards run a 2T command rate and then at 2666MHz that changes to 1T and that is why 4-DIMM 2666MHz DDR4 memory does so well. There is not a huge difference between the boards as you can see from the chart above. AMD Ryzen Single-Rank Memory Performance We start to see some differentiation between boards when looking at the write memory bandwidth and the MSI X370 XPower Gaming Titanium had rather poor 4 DIMM with regards to write memory bandwidth, but 39,200 MB/s versus 40,500MB/s isn't really a massive difference when you look at the percentage as you are looking at a mere 3% difference. AMD Ryzen Single-Rank Latency When it comes to memory latency all of the boards are close and you can see that running 4 DIMMs will give you a higher latency than just 2 DIMMs. Again, the MSI X370 XPower Gaming Titanium was slightly behind the other boards, but not by much. Let's wrap this up!

Final Thoughts and Conclusions

[caption id="attachment_192972" align="aligncenter" width="645"]AMD Ryzen X370 Motherboards and Corsair Vengeance LPX DDR4 Memory Kits What $1,925 Worth of AMD X370 Boards and Corsair DDR4 DRAM Look Like![/caption] So, after running hundreds of benchmarks we can conclude that the AMD X370 platform memory expectations greatly exceed that of what AMD claims from testing with these particular Corsair LPX DDR4 modules. Remember, AMD Ryzen platforms officially support the following memory configurations: Our testing showed that we were able to get these results: We were honestly expecting to see one AMD X370 board scale better with memory than another, but unfortunately that wasn't the case here today. That doesn't make for the most interesting charts, but we are glad that all three of these boards did well with memory. AMD and the board makers is working on improving the AMD Generic Encapsulated Software Architecture (AGESA) code and they expect that more memory improvements will be coming soon. So, maybe later we will see some differences between the memory performance on the  MSI X370 XPOWER GAMING TITANIUM ($299.99), GIGABYTE GA-AX370-Gaming 5 ($194.99) and ASUS ROG Crosshair VI Hero ($254.99) motherboards. Right now there is not a huge difference between them with regards to DDR4 memory performance and that is actually a good thing for the community! More AMD Ryzen Coverage on Legit Reviews: AMD Ryzen 7 1800X, 1700X and 1700 Processor Reviews AMD Ryzen versus Intel Kaby Lake - Gaming Performance AMD Ryzen 7 1700 Processor Overclocking AMD Ryzen 7 DDR4 Memory Scaling Performance Picking The Right AMD AM4 Motherboard For Ryzen Where are all the AMD AM4 Motherboads?