[SOLVED] Ram 3200mhz CL22 vs 2666 Cl16 ,ho is faster?

[fyeratanye]

Hy ,
i have a laptop Asus tuf a15 ryzen 7 4800h and i want to upgrede ram memory ,but now in the market ,the best memory for my laptop is kingston hyperx 3200mhz CL20 and work on my laptop .But i see 2666mhz CL16. so witch memory should i buy?

 

[siaan312]

https://notkyon.moe/ram-latency.htm
this isnt 100% the best way and doesnt account all the factors at all, but its a very good general idea of what is faster.

the 2666 cl16 kit is better

 

[utdr]

For Ryzen, between those two options, go with the faster 3200MHz RAM... because the speed of the "infinity fabric" (communication bus) within the processor is DIRECTLY tied to the speed of the RAM.

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There's a lot of factors, and one of the factors that has the largest impacts, under usual memory workloads, is the CAS latency.

true latency = time per cycle X number of cycles

or we can think of that latency calculation as the CL (number of clock cycles e.g. 16) divided by the MHz (e.g. 2666) ...

With my i3- on B365 board, I'm happy to run Kingston HyperX Predator 2666MHz CL13 ( = latency = 9.75ns )

(that's with no XMP, no overcloclocking or tweaking timings, thats just a 2x8GB kit straight off the QVL list for the motherboard)

BUT ...

With Ryzen, the speed of the "infinity fabric" within the processor is directly LINKED to the speed of the RAM.

Ryzen gets better performance with HIGHER memory clock speeds up to some point, (for sure up to 3200 MHz)

Slower RAM speed SLOWS down the infinity fabric communication in the processor, in the caches,

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For Ryzen, likely better performance (under typical workload) with the faster 3200 MHz memory vs the 2666 MHz, even with the looser timing and resulting higher "true latency".

I'm a Micron Technologies fan, so personally I would check the specs from the kits offered from the "compatibility check" on the Crucial website, and also check Kingston HyperX branded kits.

Seems like getting a CL lower than 20 on the 3200 MHz would be worth the couple extra dollars, if we want the maximum performance.

EDIT note (you probably already know this, but just in case...) if you are not replacing, but adding, a second SODIMM to the laptop, the second one will run at the same speed as the first. Both modules will run at the same speed, a faster one will get downclocked to match the slower one... for exame, if we add a 3200MHz SODIMM module into a second slot, with the first module running at 2400MHz ... they are both going to run at 2400MHz ... no performance benefit to the faster RAM.

 

[fyeratanye]

tnx for information,man i appreciate you ansuer ,i search memory for my laptop and the best memory (for now) is kinston hiperx 3200 cl 20. This memmory have 3200mhz nativ (JEDEC) profile and my cpu not suport XMP profille .
for now i wait to apearon market ather memmory ram with faster CL