Just a "how RAM works" question

[Wolrajh]

I recently came into contact with someone claiming CAS was way more important than ram speed, and should almost be the only criteria to factor in when choosing a ram kit.

They also claimed saying that "3600 is the sweetspot for am4" is stupid and moronic.

Finally, they said they'd rather get a 2666mhz CL 12 kit than a 3600 CL 15 kit.

 

Now from what I understand, the "common" formula used to calculate actual timings or "true latency", (CL/FREQ) * 1000 * 2, yields us the following score :

(12/2666)*2000 = 9.00ns

(15/3600)*2000 = 8.33ns

making the theoretical 3600 CAS 15 kit a winner. Not to mention it also gets better bandwidth, and should be a better base for OCing ?

 

As for me, I think speed and latency are obviously connected, hence the term of sweetspot after all. I'd go as far as give a little preference to speed as long as latency doesn't suffer too much ( went with 64gb 3600/17, couldn't find 16, don't know how much the ram amount and stick setup can affect latency ). You can always underclock the frequency to get good latency or something, but that's a world I do not know yet.

 

So... Are they wrong, or am I missing something fundamental here ?
 

a few links to common sources over the internet :

Spoiler

 

https://forums.tomshardware.com/threads/how-to-calculate-ram-timing.2584621/

https://www.gamersnexus.net/guides/3333-memory-timings-defined-cas-latency-trcd-trp-tras

https://www.crucial.com/usa/en/memory-performance-speed-latency

 

 

[Daniel Z.]

It is divided. The speed differences are very little if you go above 3000 on Ryzen and basically any speed for Intel AFAIK.

[i_build_nanosuits]

4 hours ago, Daniel Z. said:

It is divided. The speed differences are very little if you go above 3000 on Ryzen and basically any speed for Intel AFAIK.

(press play on the video it will start exactly at the part you guys want)

 

 

 

[Wolrajh]

One thing I forgot to mention was the context of that discussion, which is using Houdini for heavy VFX simulation work. It should put the ram under more pressure than during gaming.

Also, I vaguely mentionned am4 : consider the CPU to be at least the upcoming 3950x, which, again, considering the nature of Ryzen, could influence the importance of the memory kit specs. While 3200cl14 is still a very good combo as far as I know, I find it a bit strange to advise people to buy, like, 2666 with lowest CL (13 according to PCPP ) alongside a 3950x, especially for the aforementionned pretty intensive tasks.

I mean, even AMD recommends 3600cl16 over 3200cl14 anyway.

Spoiler

 

2 hours ago, i_build_nanosuits said:

So at least in gaming, bandwidth is indeed relevant. Some pretty important fps differences here... He doesn't mention latency though, I wonder how much it would affect his benchmarks.