What RAM CL/MHz....

[Sasherz]

So I finaly decided to upgrade my gaming rig.

New components are....

AMD Ryzen 7 1800x

Asus ROG Hero VI AM4 Motherboard

But what RAM...

Here I got the most random answers from all over dufrent places.

All from 3200 down to 2133

I know as far as low MHz tend to have a faster CL than higer MHz.

But higher MHz tend to mannage more data but have slower CL.

 

With my rig, I am going to play games and casualy stream on twitch, not much more, no heavy server tasks or movie editing.

As far as I see the lower MHz that have faster CL seems to be best.

Tops I am going to have is 32GB and might go 64GB when the price drops.

 

Im not going with G Skillz, this is simply due to theyr not that easy to get hold of where I live.

I did find this type of RAM though.

 

HyperX Savage DDR4 2133MHz 16GB

HX421C13SBK2/16

 

These looked deasent with a CL of 13-13-13 . Not the highest MHz though.

Compare to Corshair's 3200MHz with CL of 16-16-18

As I saw it, speed in CL is more importaint than the high number in MHz.

And some say the tradeoff cancles eachother out in some way

 

 

Any thoughts about this, is the RAM I found perfect for the new mobo and cpu?

 

Im not all tech guru on technical language, so please make it simple.

And if thia is in the wrong place, please move it to a correct one.

[ARikozuM]

MHz is more important for gaming and rendering, but CAS is more important when you're trying very large calculations like a protein fold or similar.

[Energycore]

For games on ryzen, fast RAM could mean big framerate gains. Check out this test.

 

So I would buy a 3200MHz kit and run it at 3600 like in the video, with looser timings.

[DocSwag]

Latency = timings/frequency. Higher MHz always means higher bandwidth, but latency also matters. If you plug it in:

 

For 2133 MHz RAM: Latency = 13 cycles/2133 million cycles/sec = 6.095*10^-9

For 3200 MHz RAM: Latency = 16 cycles/3200 million cycles/sec = 5.0*10^-9

 

So the 3200 MHz RAM actually has a lower latency.

 

Also, the clock speed of the infinity fabric in Ryzen is linked to the memory clock speed, so even more reason to get 3200 MHz RAM. It can make a substantial difference.

 

[ARikozuM]

8 minutes ago, DocSwag said:

 

Your calculation is off by about 10ns.

[DocSwag]

10 minutes ago, ARikozuM said:

Your calculation is off by about 10ns.

It is? Where did I make a mistake?

[DocSwag]

21 minutes ago, Energycore said:

For games on ryzen, fast RAM could mean big framerate gains. Check out this test.

 

So I would buy a 3200MHz kit and run it at 3600 like in the video, with looser timings.

Unfortunately it's mostly only Samsung B-Die RAM that can reach much more than 3200 MHz, and that stuff is hard to come by. You're guaranteed to get it with higher frequency G Skill RAM but OP can't really get G Skill. With other's like Corsair it's luck of the draw  

[Energycore]

Just now, DocSwag said:

Unfortunately it's mostly only Samsung B-Die RAM that can reach much more than 3200 MHz, and that stuff is hard to come by. You're guaranteed to get it with higher frequency G Skill RAM but OP can't really get G Skill. With other's like Corsair it's luck of the draw  

Ah that sucks. Well, other sticks shouldn't have a problem doing 2933 right?

[DocSwag]

Just now, Energycore said:

Ah that sucks. Well, other sticks shouldn't have a problem doing 2933 right?

If they're guaranteed for 3200 MHz, then I assume they can do 2933 . Not too sure about sticks that are rated for less. Not too knowledgeable, I'd imagine most could but I'm not sure if all can.

 

[ARikozuM]

16 minutes ago, DocSwag said:

It is? Where did I make a mistake?

CL/(0.50MHz x 1000) = ns

 

Also, CAS latency is a rough estimate of the total timings. Each of the 3 "words" can be used to narrow the overall latency to what you would see in real time. 

 

@Sasherz Don't think of MHz as "faster" but "wider". You're moving more info at once rather than the same amount but faster.

[DocSwag]

1 minute ago, ARikozuM said:

CL/(0.50MHz x 1000) = ns

 

 

? Not sure I understand? I gave my answer in seconds anyways, not ns or ms.

[ARikozuM]

Just now, DocSwag said:

? Not sure I understand? I gave my answer in seconds anyways, not ns or ms.

2133/13

13/(.5*2133*1000) = 1.22ns not .6095ns

3200/16

16/(.5*3200*1000) = 1ns

 

[Guest]

If you haven't bought anything yet I would suggest the R7 1700 over the 1800X. Overclock it yourself and save some money. You should be able to get 3.8GHz - 4GHz depending on the cpu with a good 240mm/280mm AIO or high end air cooler.

 

As for the Ram go with a 3000MHz or above. As mentioned by Energycore it can make a big difference.

[DocSwag]

17 minutes ago, ARikozuM said:

2133/13

13/(.5*2133*1000) = 1.22ns not .6095ns

3200/16

16/(.5*3200*1000) = 1ns

 

oh oops I forgot about DDR .

 

But why the times 1000?

[ARikozuM]

 

Quote

But why the times 1000?

No clue.

[DocSwag]

2 minutes ago, ARikozuM said:

 

No idea. That's how the equation goes. You'd have to ask whoever made RAM (or memory controllers) in the first place.

?...

[ARikozuM]

Just now, DocSwag said:

?...

It's to convert to nanoseconds rather than milliseconds. 

[DocSwag]

7 minutes ago, ARikozuM said:

It's to convert to nanoseconds rather than milliseconds. 

But why would it have been in milliseconds in the first place? MHz is millions of clocks/sec, not millions of clocks/millisecond.

[ARikozuM]

Just now, DocSwag said:

But why would it have been in milliseconds in the first place? MHz is millions of clocks/sec, not millions of clocks/millisecond.

Like I said, I have no idea. 

[DocSwag]

4 minutes ago, ARikozuM said:

Like I said, I have no idea. 

...

 

Not sure I'm gonna agree with that then...

[ARikozuM]

1 minute ago, DocSwag said:

...

 

Not sure I'm gonna agree with that then...

Wikipedia formally(?) lists the calculation as "(CAS / Frequency (MHz)) × 1000 = X ns".

 

Thereby omitting DDR from the equation.

[DocSwag]

20 minutes ago, ARikozuM said:

Wikipedia formally(?) lists the calculation as "(CAS / Frequency (MHz)) × 1000 = X ns".

 

Thereby omitting DDR from the equation.

I would imagine that would be CAS/Frequency(KHz) which would give the answer in 1000s of seconds lol. Not sure what the heck they're doing  

[ARikozuM]

Just now, DocSwag said:

I would imagine that would be CAS/Frequency(KHz) which would give the answer in 1000s of seconds lol. Not sure what the heck they're doing  

You're dividing by 1000 which makes the value 1/1000th of what it would be.

[DocSwag]

4 minutes ago, ARikozuM said:

You're dividing by 1000 which makes the value 1/1000th of what it would be.

Wait it would've been cycles/millions of cycles/sec which would give sec/million. Dividing by another 1000 would give you the measurement in billions of secs...

[ARikozuM]

3 minutes ago, DocSwag said:

Wait it would've been cycles/millions of cycles/sec which would give sec/million. Dividing by another 1000 would give you the measurement in billions of secs...

Which is what a nanosecond is.