[SOLVED] How to understand CAS Latency Timings

57vroom

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Aug 25, 2011
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How does one make heads or tails from the difference in RAM and the aspect of CAS latency?

Specifically, which of these are better in an AS Rock B450 Pro4:

Memory TypeDDR4DDR4
Pin Configuration288-pin288-pin
Memory SpeedPC4-21300PC4-25600
Memory Speed (MHz)DDR4-2666DDR4-3200
Memory Capacity16GB (2 x 8GB)16GB (2 x 8GB)
Memory ChannelsDualDual
Number of Modules22
Voltage1.2V1.35V
CAS Latency1516
Memory Latency Timings15-15-15-3516-18-18-38
ECCNon-ECCNon-ECC
Buffered/UnbufferedUnbufferedUnbuffered
 
Solution
DDR4 base memory frequency is 2133MHz so any memory with XMP above that is overclocking, it's jut that XMP is settings for automatic overclock which you have to activate/enable in BIOS. So, either of those 2 RAMs would work at 2133MHz if you don't overclock them (set XMP).
As Ryzen likes faster RAM and if you are going to use built in GPU, 3200MHz would be better even with higher CAS Latency.
IGPU uses system memory so faster is better. 2 x 8GB 3200 MHz would be ideal. Color is least important part and would be foolish to sacrifice performance for looks unless you frame it and nail to a wall.
DDR4-3200 is for overclocking as it is faster than DDR4-2600 which is a more conservative clock speed. Your choice of CPU usually determines what officially supported memory clock speeds run at as well as possible overclocking speed memory.

CAS latency with a lower number means tighter timings. A higher number means timings are more relaxed. Memory specifications usually determine what the optimal timing settings are for a kit of memory.

Which one to choose would depend on the CPU used and your overclocking preferences.
 

57vroom

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So if both are priced the same [Gskills @ Microcenter], and I have no intention of overclocking at this point [Ryzen 2200G], just buy whichever I like the looks of better?

One is RED and the other is BLACK.
 
DDR4 base memory frequency is 2133MHz so any memory with XMP above that is overclocking, it's jut that XMP is settings for automatic overclock which you have to activate/enable in BIOS. So, either of those 2 RAMs would work at 2133MHz if you don't overclock them (set XMP).
As Ryzen likes faster RAM and if you are going to use built in GPU, 3200MHz would be better even with higher CAS Latency.
IGPU uses system memory so faster is better. 2 x 8GB 3200 MHz would be ideal. Color is least important part and would be foolish to sacrifice performance for looks unless you frame it and nail to a wall.
 
Solution