Ryzen RAM

[RAM555789]

Looking around on the fourms I have seen people talking about "Ryzen RAM" and I am instrestead in the impact RAM has on Ryzen, and how much RAM I should have for gaming, streaming and recording.

[KenjiUmino]

1 minute ago, RAM555789 said:

Looking around on the fourms I have seen people talking about "Ryzen RAM" and I am instrestead in the impact RAM has on Ryzen, and how much RAM I should have for gaming, streaming and recording.

from what i read, the question is not "how much" but rather "how fast"

[Terryv]

Ryzen seems to favor high ram speeds. This is due to the way the cores communicate with each other between CCX's.

 

How much ram is irrelevant for ryzen performance as long as you have enough for your uses

 

The sweet spot so far seems to be 3200 MHz. Some people have gotten as high as 3600 MHz and it still scales well, but getting speeds that high working isn't consistent yet.

[TVwazhere]

(spoiler alert, yes. Yes it does)

[DocSwag]

With Ryzen, AMD created something called a CCX, or CPU Core Complex. These CCXs each include 4 cores and 8mb L3 cache. On the R7 CPUs, AMD basically used two CCXs to make an 8 core CPU with 16mb L3 cache. They then used he infinity fabric, something they created, to connect the two CCXs together. The reason this was done is because making two quad cores is a lot easier than one octa core. It probably woulda take them at least another month or two on the design tables to create a "true" octa core die.

 

Now the thing is, the clock speed of the infinity fabric that connects the two CCXs together is directly linked to the clock speed of the memory. Because DDR is double data rate, and the infinity fabric is SDR or single data rate, if you look at the theoretical clock speed of DDR4 RAM and cut that in half that's the clock speed of the infinity fabric (if you have 2400 MHz RAM the infinity fabric would be clocked at 1200 MHz). If you want to see all the nice lil math for the bandwidth through the CCXs at certain clock speeds you can look here:

What I failed to mention in that post was that I'm not sure but there could also be a decrease in latency if you increase the infinity fabric clock speeds, assuming that the #cycles it takes for data to go through the fabric is constant (which I think it is).

 

Testing from multiple sources has shown that Ryzen will get a much larger performance boost in gaming from overclocking memory than overclock the CPU itself. Going from 2133 MHz to 2933 can yield as high as a 10% performance jump.

 

3200 MHz is about the point at which you should buy RAM at, since after that prices go up quite sharply and before 3200 MHz the prices don't increase too much. This is the reason why most of us recommend using 3200 MHz ram, preferably from g skill since their ram uses Samsung b die which has shown itself to like Ryzen better than other ddr4 ram and also because it OCs better so if you ever wanna go past 3200 you're more likely to be able to.

[gh0st68]

I bought G skill Flare X 3200 16 gigs