As far as components go, RAM is one of the most crucial parts of any build. It can directly influence speed, responsiveness, and performance of your computer and should be chosen wisely.
The reason why you should choose compatible RAM for AM4 CPUs and motherboards is: To ensure hassle-free plug-and-play operation, seamless usage, and for the best performance possible.
Below, we’ll discuss in detail what RAM is, how it works, why it is important, its relation to AM4 CPUs as well as impact on performance, and how to choose compatible RAM for your AM4 platform.
What is RAM?
RAM is an acronym that stands for “Random Access Memory”. RAM is an ultra high speed, low latency device where data is loaded from storage and temporarily placed to be directly accessed and/or changed by the CPU, as storage cannot provide speeds fast enough to keep up with the CPUs need for speed.
What Types of RAM are There?
There are different types of RAM, including DDR2, DDR3, DDR4 for CPUs; and GDDR5, GDDR6, and HBM for GPUs.
But the most relevant here is DDR4, and is the RAM that the AM4 platform uses exclusively. Other types of RAM will not be compatible, so our discussion will solely focus on DDR4.
“DDR” means “Double Data Rate” meaning for every clock cycle, data can be transferred or accessed twice.
RAM is sold and marketed at it’s effective speed, but some software will read it’s base speed (ie. 1600 MHz is the base speed of a 3200 MHz kit).
A question i have been asked a number of times is “does DDR3 RAM work with AM4?”. Follow the link if you would like to know more of the topic.
Understanding RAM Speed, Timings, and Capacity
RAM comes in different speeds, different latencies, and different capacities (size).
Speed is measured in frequency, or MHz, and higher is usually better, as it provides more bandwidth, meaning more data can be read/written at once. But after a certain point you’ll see diminishing returns on performance.
Latency is measured by primary timings. Arguably the most important timing is CL, or CAS Latency, and is measured in clock cycles taken to complete the operation. Lower is better when comparing similar frequency RAM.
However since latency is rated clock cycles and not by nanoseconds, the higher frequency you have, the shorter the time it takes to complete those clock cycles.
This is why 3600 MHz CL16 has effectively lower latency than 3000 MHz CL14, while also having higher bandwidth.
To calculate your overall latency, this website: https://notkyon.moe/ram-latency.htm offers a useful and easy way to figure it out
Capacity is measured in GB, and DDR4 sticks can come in sizes of 4GB, 8GB, 16GB, and 32GB,. There are 64GB and 128GB sticks, but these are generally for server and HEDT use only, and the majority of AM4 CPUs and motherboards don’t support sizes that large.
Kits that are the most popular are usually 2x8GB sticks, 4x8GB sticks, or 2x16GB sticks.
Single Channel vs Dual Channel for AM4 CPUs
AM4 CPUs have 2 memory channels, and support 2 RAM sticks per channel (4 slots overall on the motherboard). The minimum requirement for dual channel to work is 1 stick per channel (2 sticks in total).
Dual-channel mode effectively doubles your bandwidth and increases your performance noticeably overrunning a single stick of RAM. This is especially noticeable on AM4 CPUs as they are memory dependent.
It is generally recommended to have at least 2 sticks of RAM to take advantage of this performance, even if it means running 2 smaller capacity sticks vs a single large capacity stick.
RAM and Its Relation to Performance With AM4 CPUs
AM4 CPUs directly benefit from faster memory. The reason for this is that the clock speed for the CPU’s Infinity Fabric, the communication mesh inside the CPU that connects everything together, is directly tied to the memory speed. It also benefits from lower latency as well.
Ryzen 1000 and 2000 series CPUs Infinity Fabric cannot be controlled manually, but with Ryzen 3000 and 5000 series CPUs, the Infinity Fabric clock (or FCLK) is manually adjustable, and scales all the way to 1800-1900 MHz.
This speed is generally synced up with the memory controller, and your memory’s base speed (so 1900 MHz would mean your memory would be running at 3800 MHz if they are synced).
Because the Infinity Fabric is tied into everything, running it at a faster speed means better performance overall. You can run the Infinity Fabric out of sync with your memory, but this comes at a latency and performance penalty, and is generally not worth it.
Using RAM frequencies that are above the maximum speed your FCLK can handle is also not beneficial either as this will cause your memory controller to run in 2:1 mode, effectively lowering your FCLK to half of your memory’s base clock.
Finally, how to Choose Compatible RAM for AM4
With the information above, you should be able to get an idea of what kind of RAM you want for your AM4 setup. The best way to tell if your RAM will be compatible is to look at your motherboard’s QVL list. This can be found on your motherboard manufacturer’s website.
To do this, go to your manufacturer’s website, search for your motherboard model then click the relevant link. Once there, click the “Support” tab. In the “Support” tab, there should be a sub-section titled either “Compatibility”, “CPU/Memory Support”, or “Support List”.
Under either of these tabs, you’ll find memory compatibility or QVL lists for each different generation of CPU, as your memory support will depend on which generation of CPU you’re using.
The other way is look for memory kits that are branded specifically for AMD Ryzen use. Typical kits are G.Skill’s FlareX and TridentZ Neo line, Corsair’s Vengeance series, Crucial’s Ballistix series, or almost any of TEAMGROUP’s offerings.
Despite this, you should still reference these kits with your motherboard’s QVL/memory compatibility list to ensure compatibility.
There are sweet spots for frequency that give the best performance. You don’t necessarily have to buy kits in this sweet spot, but we’d recommend no lower than 3000 MHz for good performance.
Each generation is different and these sweet spots are as follows:
> 3000-3200 MHz for Ryzen 1000/2000 series CPUs, and 2000/3000 series APUs
> 3600 MHz for Ryzen 3000 and 5000 series CPUs, and 4000 series APUs
If you were just looking for a way to find compatible RAM for the AM4 platform or wanted to learn more about RAM, we decided to cover the most important details for you so that you can make a more informed purchasing decision.
Having gone over the essentials, figuring out what RAM to buy, and choosing a compatible AM4 RAM kit should be a breeze. With the guarantee of compatibility, it offers you peace of mind that your build will go smoothly and seamlessly.
Here is an article I wrote all about the absolute best AM4 motherboards that money can buy right now that I think may be of some use for you.
James Cosgrove has been the lead writer at GizmoFusion since 2019. He has a huge passion for the latest technology and gadgets. He loves to talk and write about this interest. He hopes that visitors to the website will find his reports informative and helpful when it comes to making the best choices for their needs.