The board I’m looking at for my new Ryzen 7 2700X build can handle all RAM speeds for the most part. I’m trying to figure out the most stable RAM speed for this chip under unRAID but I’m finsing all kinds of information that contradicts itself.

 

As of January 2019, is there any problem with 3200 speed with unRAID?

 

What’s the best RAM speed choice under unRAID with Ryzen 7 2700X?

Edited January 9, 20197 yr by ksignorini
Solved.

2 hours ago, ksignorini said:

is there any problem with 3200 speed with unRAID?

The problem isn't Unraid, the problem is that you can have memory errors if overclocking the RAM with Ryzen CPUs, several cases on the forum where users were having sync errors on the parity check because of that, IMO, if you care about the data on the server, limit you RAM speeds to max officially supported without overclocking:

 

I knew I saw that chart somewhere before!

 

Now to figure out the ranking of the RAM I was looking at...

Edited January 5, 20197 yr by ksignorini

I've had gskill (samsung b-die) ram running at it's vendor rated speed of 3200mhz @C14 on 1st gen threadripper unraid build for 11 months.

Has run without issue and was tested heavily before going "live" on my system.

 

My 2c, don't cheap out on ram, particularly if you want to run above base supported speeds. 

Definitely would recommend running extended memtests once you make your purchase to validate all is ok, I ran mine for nearly a few days.

 

Edited January 5, 20197 yr by tjb_altf4

You should check the motherboard manufacturer's website for best memory compatibility and do not gamble, the Ryzen is very selective when it comes to DDR.

 

I got my Ryzen 1700x & Asus Prime X370 (capable off 3200MHz) about two years ago together with my first unraid, till I figured things out why the system was crashing a lot I was faced with memory comparability for the first time that I never saw in my 20 or so of years of building PCs.

 

My memory is CMK16GX4M2B3200C16 3200 but with the latest bios & the help of reddit users it is currently clocked at 3000MHz but the timings are at 16, 16, 16, 16 36.

The PRIME X470 mobo that I'm looking at supports damn near everything out there:   https://dlcdnets.asus.com/pub/ASUS/mb/SocketAM4/PRIME_X470-PRO/PRIME-X470-PRO-memory-QVL-Ryzen-2nd--Generation-processors.pdf

 

Please help me get this right, if you don't mind. If I go with 2/4 slots filled with 2x16GB sticks, if they're dual rank, then I have to stick to 2400 MHz? If I go with 2/4 slots filled with single rank, I can go with 2933 MHz?

 

So if the CPU has these limitations why would the mobo support so much more if the CPU doesn't?

Edited January 5, 20197 yr by ksignorini

...and the other problem is that I can't buy 2400MHz anymore in my city. And I kinda wanted to buy it, maybe, well, maybe, today....

 

I can get 2666MHz in a stick supported by this mobo.

 

Argh.

 

Thoughts?

I've also seen, in various places online, that you should get the fastest RAM supported by your chip for Ryzen. What's up with that? (It's totally counterintuitive to me.)

I bit the bullet and bought the Ryzen 2700X with Asus PRIME X470-Pro and 2666 MHz Kingston RAM. 

 

I'll keep you posted...

On 1/5/2019 at 3:04 PM, ksignorini said:

I've also seen, in various places online, that you should get the fastest RAM supported by your chip for Ryzen. What's up with that? (It's totally counterintuitive to me.)

I believe this is because in the Ryzen architecture the infinity fabric is clocked based on the RAM speed. Thus RAM speed effects not just how fast data can be moved to and from RAM but also how fast data can be moved around within the processor and to the peripherals.

Edited January 7, 20197 yr by primeval_god

@leonardwulf

These two articles have some more in depth infor on it https://www.tomshardware.com/reviews/amd-ryzen-5-1600x-cpu-review,5014-2.html, https://www.anandtech.com/show/14525/amd-zen-2-microarchitecture-analysis-ryzen-3000-and-epyc-rome/11. The short of it though is that in the first 2 generations of Ryzen, the infinity fabric, which is the internal interconnect between Ryzen's core complexes, memory and peripherals, is clocked 1:1 with the RAM. Thus the speed at which your RAM runs directly determines the speed at which data can be moved around within the Ryzen processor.