My QVL Memory Kit "Silently" removed from QVL List

PatriotVipers wrote: xhue wrote: No matter what brand or model you decide to stick to, choose the smallest possible CL-number aka CAS latency. For example CL11 @ 2400MHz has same performance as CL18 @ 3600MHz. Do some reading on the topic if you wish. Oh, I've done a lot of reading to try and figure this all out but there is so much to learn it boggles my mind. Please, if you can, help me understand as a simpleton.   So then if we say that: 2400MHz = PC19200 = 19.2 GB/sec x 2 = 38.4 GB/sec 3600MHz = PC28800 = 28.8 GB/sec x 2 = 57.6 GB/sec We can see, obviously, that the faster MHz memory has more "maximum theoretical bandwidth" than the slower MHz memory. So my question is, how are the performances considered equal? Can we split the "maximum theoretical bandwidth" into different parts to show why this is the case? Is one part raw data and one part overhead? Or just lost cycles because the memory has to wait for some reason or another? Can we assign an efficiency rating by saying: 3600MHz with CAS Latency of 18 is 80% efficient so we get an actual usable bandiwdth of 57.6 GB/sec x .8 = 46.08 GB/sec. Is that kind of what's going on?

Here is the deal.

Speed comes in 2 flavors when talking RAM - latency and bandwidth.

Latency - how quick memory can store or retrieve a given data word. Measured in clock cycles or nanoseconds.

Bandwidth - How many data words can memory store or retrieve at once. Measured in MT/s and it's direct derivative from 'MHz'. That's the numbers you were quoting. Say, some workload needs 1000MB of RAM data at once - that's no biggie, all RAM can do it in a single 'tick'. Say, however other app needs 10GB of RAM at once - if RAM doesn't have that bandwidth it needs to do a few more 'ticks', each of them taking x CAS latency (clock cycles).

Check here for more info:
https://www.pcsteps.com/7932-real-ram-speed-mhz-cas-latency/

https://en.wikipedia.org/wiki/CAS_latency

EDIT: Ryzen's CCX InfinityFabric inherits the RAM MHz, i.e. if the RAM is 3200MT/s, the CCX's will 'talk to each other' @ 1600MHz. That's why Ryzens love the RAM MT/s.




Edited by xhue - 31 Aug 2018 at 1:46am

Okay,

Edited by PatriotVipers - 31 Aug 2018 at 2:59am

heheh patriot are still using old method of using serial # to identify chips either way your timing looks funny (16-15-16-36) as its not on your spd