WoW performance with different RAM configurations

RAM plays a role in game performance. It's quite important for integrated graphics but even with discrete graphics RAM configuration or frequency may affect the CPU performance. Let's check how WoW performance depends on RAM for AMD Ryzen and Intel Coffee Lake systems.

Gaming and RAM

RAM has an effect on you PC performance. Assuming you have enough memory things like frequency or latency of your RAM sticks may alter your in-game FPS by few or bit more percent. If you are using an integrated GPU then your system RAM will have even greater impact on your gaming performance.

In this article I'm going to benchmark World of Warcraft 8.3 with various RAM configurations to showcase what are the best and optimal configurations - for dedicated GPU setups only. I'm planning integrated graphics optimization and benchmark article later on.

If you are building a PC you should pick a good memory kit based on picked CPU and motherboard chipset. Ryzen platforms benefit more from faster RAM and support it more often. Intel platforms benefit less and aside of high-end chipsets do not support overclocked RAM speeds which may lock you down to like 2666MHz with Coffee Lake.

If you have an existing PC and you want noticeably more performance then better RAM isn't the thing that will give it to you – most performance comes from CPU and GPU.

RAM basics

Memory bandwidth determines how fast data can be sent or received from memory. The more the better, especially when large amount of data must be transferred. CAS latency is a delay between receiving a command from memory controller to finalizing that command. The shorter latency the better.

With technology advancement RAM frequency increases which increases memory bandwidth. 1333 MHZ/PC3-10600 bandwidth is 10,6 GB/s or 1333 MT/s (megatransfers per second), 1600 MHz/PC3-12800 is 12,8 GB/s or 1600 MT/s and 2133MHz is 17 GB/s or 2133 MT/s. Modern DDR4 RAM sticks can run at 3600 MHz quite easily where as for 4000MHz we will pay a premium. Do note that you can't just use the fastest RAM on the market - it must be supported by your CPU and chipset which may not be the case.

CAS latency seems to increase with increasing memory frequency, but that's not actually what's happening. The number given as CL latency is a number of clock cycles. The duration of a clock cycle decreases with increasing RAM frequency so actual latency stays at the same level or slightly decreases. 1333MHz/CL9 latency is 13.50 ns, 1600MHz/CL11 is 13.75 ns and 2133MHz/CL14 is 13,12 ns.

The bandwidth between RAM and memory controller can also be doubled by using two identical memory DIMMs working in dual channel mode. On motherboards you have to put RAM in two matched DIMM slots for it to work. On workstation platforms like for Threadripper you have access to more memory channels allowing for even bigger bandwidth. It can be important for compute tasks but much less for gaming.

Test platform

The tests were done on two systems - Ryzen 5 3500X and Intel i5-9400F with Vega 64 graphics card. Ryzen was on a B450 board while Intel on Z390.

RAM configurations for Ryzen system:

• 2 x 4GB CL17 2400MHz: Crucial CT4G4DFS824A
• 1 x 8GB CL17 2400MHz: Crucial CT8G4DFS824A
• 2 x 8GB CL15 2133MHz: G.Skill Ripjaws V F4-3200C15D
• 2 x 8GB CL15 3200MHz: G.Skill Ripjaws V F4-3200C15D
• 2 x 8GB CL15 3733MHz: G.Skill Ripjaws V F4-3200C15D

RAM configurations for Intel system:

• 2 x 8GB CL15 2133MHz: G.Skill Ripjaws V F4-3200C15D
• 2 x 8GB CL15 3200MHz: G.Skill Ripjaws V F4-3200C15D

WoW was tested on mode 7 at 1080p without any addons and with FPS limiters off. Benchmarks were done on patch 8.3.0.33724.

Results

Single vs Dual channel RAM

There is a lot of single vs dual channel benchmarks out there. Dual channel often gives few more FPS in games if the system isn't bottlenecked heavily by the dGPU or CPU.

Some laptops or pre-built PCs may come with one RAM DIMM making them work in single channel. When building a PC you can see 2 x 8 or 1 x 16GB kits. With single bigger DIMM you can add another one later on for 32GB dual channel configuration, but until that happens you are working in single channel... and do you really need 32GB of RAM?

To compare single vs dual channel I used Crucial RAM kits working at 2400MHz CL17 so that only channels count is the variable in the tests:

As you can see we gain around 10%+ when moving from single to dual channel configuration.

RAM frequency for Ryzen system

Similarly also in this case you can find a lot of gaming benchmarks showcasing memory frequency effect on gaming performance like this one at purepc.pl (multiple games tested, but not WoW).

For Ryzen CPUs RAM frequency has an additional effect as it drives the clock at which Infinity Fabric works - the interconnect through which CPU components talk to each other. That's why it's quite important to pick a fast kit for Ryzen CPU. Second gen Ryzen (3000 desktop series) supports 3600MHz RAM as base and it's somewhat likely that third gen Ryzen (4000 desktop series) will move the base supported frequency higher. Memory XMP profiles are supported which allow using memory kits running even above 4000MHz but the higher you go the more limited support can get and you may run into stability problems. 3600MHz should be enough.

As you can see moving from 2133 CL15 to 3200 CL15 improves performance, even by around 15%. This isn't reflected by every test scenario. Karazan combat test reacted less while Stonard is likely limited by other factors. 2x4GB 2400MHz CL17 Crucial kit also performs really well. This can be due to latency or how tight timings the system managed to get.

3733MHz wasn't stable so I run only few benchmarks. It's above what this memory kit supports and manual OC may or may not work. With manually setting timings and other stuff there is a chance to make it stable but for new purchases it's just better to pick 3600MHz RAM which has good prices. Higher frequencies are premium right now. Also do note that the system booted and tha game run fine - but with random memory related crashes while playing.

RAM frequency for Intel system

Intel has a ring bus for the inter core communications and RAM doesn't play a crucial role there. Still there will be some uplift in performance with higher frequency RAM. Most non-enthusiast systems may be limited to 2666MHz (with Coffee Lake, older platforms will have other supported frequencies) even when having faster RAM.

For Intel the gains are lower than for Ryzen, although not that clearly. Dalaran gains a lot, similarly Stonard which wasn't reacting that much to RAM kits on Ryzen. Other scenarios see around 10% uplift.

The system was unable to boot at 2733MHz OC but I didn't went deep into manual settings with this.

Intel versus AMD

i5-9400F and R5 3500X are 6 core 6 thread CPUs. How do they compare to each other when running 3200MHz RAM?

Intel has an edge in empty zone scenarios like Stonard and empty Karazan but on 1% low AMD is slightly better. In modern zones like Dazar'alor and Boralus flyby Ryzen achieves higher FPS and more importantly - higher 1% low FPS which is important for game fluidity.

Summary

As in other games faster RAM is better than slower one. Dual channel is better than single channel. Actual gains will vary depending what other components you have.

You don't really have to go all in with RAM. Using RAM on CPU nominal frequency will be enough. If you have an enthusiast platform that supports higher frequencies and you sure given kit will be compatible and stable and you are ok with the premium - the choice is yours.

Important thing to note is that when you install new DDR4 RAM it will likely default to 2133 MHz and you will have to go to PC BIOS and select the XMP profile yourself.

WoW scales with RAM channels/frequency but it's not ground breaking - with weak GPU or CPU you should think about replacing those instead of RAM and if you have a modern RAM with bleeding edge CPU and GPU then performance problems aren't likely due to RAM (unless there is some issue with how it works or was configured).

As for amount - 8GB seems fine when WoW is the only app running (no Discord, browser etc.) and no addons. The whole system was using bit above 5GB of RAM during gameplay. For any new and modern system I would however advise 16GB - 2 x 8GB. 3600MHz RAM got cheap where as 3200MHz could be on a sale here and there. Just check explicitly what your motherboard supports if planning any changes (especially on Intel side).