Question CL19 / CL17?

Nov 28, 2021
25
1
35
0
Hey i have a question. I was thinking about buying some ram. But i ran into a problem that i need answered.

It's simple i found a 4000Mhz ( Patriot Viper Steel 2x8 ) one, and a 3600Mhz ( Kingston Fury Beast 2x8 ). But here comes the problems. I dont want to make a mistake because the 4000Mhz one is CL19, but the 3600Mhz one is CL17.

Is it gonna make much difference, and which one's should i buy if it doesn't make much fps differnce.
 
Nov 28, 2021
25
1
35
0
Also how do i check or can someone check the compatibility, am i able to buy 4000Mhz ram on my motherboard or proccesor.

AMD Ryzen 5 2600x
ASUS ROG STRIX B350-F GAMING
 

Eximo

Titan
Ambassador
The CL numbers aren't just there for matching. Mhz is incorrectly applied (The actual Mhz is half that number). And just matching the latency isn't really enough, all the timings should match for memory pairing, which I'm not sure is part of the question anyway.

DDR4 4000 MT/s (Not Mhz if we are getting pedantic) at CL19 is going to have a total latency of of 8.451 ns (nanoseconds)
DDR4 3600 at CL17 is going to have a latency of 9.444ns
To get close to matching DDR4 4000 at CL19 you would have to go as low as CL14 on 3600,

Now the 4000 does also have more bandwidth, but I am guessing the price difference is quite significant.
 
Last edited:
Reactions: Hellfire13

DimkaTsv

Great
Nov 7, 2021
156
23
95
3
DDR4 4000 MT/s (Not Mhz if we are getting pedantic) at CL19 is going to have a total latency of of 7.451 ns (nanoseconds)
? Are you sure you didn't miscalculated for 4400MT? Hell even for 4400 CL 19 is 8.(63) ns
1/(4000/2)*19=0.0095 = 9.5ns
1/(3600/2)*17=0.009(4) = 9.(4) ns
Yeah, 3600 one is still a bit better in terms of latency, but slower in terms of data transfer speed imo... But it will actually heavily depend on subtimings, as they can mess up XMP a lot sometimes
 
Nov 28, 2021
25
1
35
0
It says 3200 and something if overclocked even more beyond. So am i good? Is it gonna like think if i put 4000Mhz that it's overclocked? Or it doesn't work like that?
Exact sentece from the official rog site: "With support for DDR4 memory, ROG Strix B350-F Gaming lets you drive memory frequencies to 3200MHz and beyond when overclocked! ASUS-exclusive T-Topology circuit design provides superb memory-overclocking capability to unleash the full power of DDR4 by minimizing coupling noise and signal reflection. "

 

Eximo

Titan
Ambassador
You could try Googling “ASUS B350-F GAMING max ram speed”
And this, is sort of useful, but really the compatibility list can be had here:

https://dlcdnets.asus.com/pub/ASUS/mb/SocketAM4/STRIX_B350-F_GAMING/ROG-STRIX-B350-F-GAMING_Memory_QVL_180125.pdf

Looks like ASUS only tested up to 3200 kits for this board, which is probably appropriate for Ryzen 1000 and 2000 series chips that this board was expecting. A 3000 series chip would also likely stop around 3200, but it depends on how good the CPU is.
 

Eximo

Titan
Ambassador
? Are you sure you didn't miscalculated for 4400MT? Hell even for 4400 CL 19 is 8.(63) ns
1/(4000/2)*19=0.0095 = 9.5ns
1/(3600/2)*17=0.009(4) = 9.(4) ns
Yeah, 3600 one is still a bit better in terms of latency, but slower in terms of data transfer speed imo... But it will actually heavily depend on subtimings, as they can mess up XMP a lot sometimes
Sorry that should have been an 8, I think. Need to doublecheck my formula. Either way, I would pick a nice low latency 3200 kit for that CPU.
 

DimkaTsv

Great
Nov 7, 2021
156
23
95
3
Having 4000 mhz ram might not be a bad idea if you plan to overclock, but if you don’t then stick to 3200mhz.
He will 99% likely not be able to even run this memory with 4000MT XMP, because memory controller on CPU wouldn't be able to catch up.
So he can buy it ofc, but will be forced to downgrade that XMP to something more appropriate, like 3200 CL14, maybe, if possible to get second XMP profile?
But memory timing setting is a lot of work with a lot of long tests and pretty tough to do without a lot of knowledge
 

DimkaTsv

Great
Nov 7, 2021
156
23
95
3
Sorry that should have been an 8, I think. Need to doublecheck my formula. Either way, I would pick a nice low latency 3200 kit for that CPU.
Btw these somehow are even more expensive than that Patriot Viper 19-19-19
Like 60% more expensive for me.

And Patriot Viper is around 20% more expensive than Kingston Fury Renegade, but still in very reasonable borders... imo want to buy it myself in 3 weeks). But i do have Ryzen 5 5600X
 

DimkaTsv

Great
Nov 7, 2021
156
23
95
3

Eximo

Titan
Ambassador
A closer look at those 3200+ ratings shows they didn't always test the kits at full speed, they were just going for compatibility.

I would go with the Kingston kit. CL17 isn't wonderful though, if you can track down a 15/16 kit that would be a little better.
 
Reactions: DimkaTsv

DimkaTsv

Great
Nov 7, 2021
156
23
95
3
A closer look at those 3200+ ratings shows they didn't always test the kits at full speed, they were just going for compatibility.
Hey, i still wouldn't decline myself from Samsung B-Die kit)
And i sent him a name for 3600 CL16 kit he probably can buy
 
Nov 28, 2021
25
1
35
0
A closer look at those 3200+ ratings shows they didn't always test the kits at full speed, they were just going for compatibility.

I would go with the Kingston kit. CL17 isn't wonderful though, if you can track down a 15/16 kit that would be a little better.
You mean if i can find a CL15/16 ? But at what Mhz Max?
 

ASK THE COMMUNITY

TRENDING THREADS