What exactly are read and write speeds for RAM?

[TheBiggestOfBuschemis]

So I just wanted to know. What exactly do we mean by "read speed" and "write speed" for RAM? Like what exactly are those two things? 

[Electronics Wizardy]

How fast the cpu can read and write data to ram?

[Eigenvektor]

The speed at which you can read and write data to and from RAM (e.g. MB/s)

[ddennis002]

4 minutes ago, Eigenvektor said:

The speed at which you can read and write data to and from RAM (e.g. MB/s)

We don't measure RAM speed by MB/s as a standard.

Ram is measured by MT/s (Megatransfers per second)

There is read and write latency speed of ram which is measured in nanoseconds

10 minutes ago, TheBiggestOfBuschemis said:

So I just wanted to know. What exactly do we mean by "read speed" and "write speed" for RAM? Like what exactly are those two things? 

What exactly are you trying to figure out?

[TensorVortex]

A rough number would be around 40GB/s for single channel.

[ddennis002]

3 minutes ago, TensorVortex said:

A rough number would be around 40GB/s for single channel.

Your about spot on as an average but that would be at dual channel.

[TensorVortex]

5 minutes ago, ddennis002 said:

Your about spot on as an average but that would be at dual channel.

Oh whoops i think I fked up the number. I forgot my threadripper is quad channel.

 

[ddennis002]

1 minute ago, TensorVortex said:

Oh whoops i think I fked up the number. I forgot my threadripper is quad channel.

 

All good DDR4 Depending on the speed dual channel ranges from 30GB/s to 60GB/s. 

Quad channel again ranges from about 50GB/s to 80GB/s again depending on memory speed being used.

[Sakkura]

36 minutes ago, ddennis002 said:

We don't measure RAM speed by MB/s as a standard.

Sure we do. That's what the numbers are in PC4-19200 for example. That's the other name of DDR4-2400.

[porina]

Consider if we're talking about peak or practical throughput. As an easy reference point, dual channel 3200 is about 50GB/s in theory. If you run aida64 bandwidth tests or similar, you will get somewhere below that. If you manually tune timings, you can creep closer to the theoretical.

[Eigenvektor]

2 hours ago, ddennis002 said:

We don't measure RAM speed by MB/s as a standard.

Ram is measured by MT/s (Megatransfers per second)

There is read and write latency speed of ram which is measured in nanoseconds

What exactly are you trying to figure out?

In was trying to express it in a way that is easy to understand. Everybody else in this thread seems to use MB/s too.

 

If you understand Internet speeds or transfer speeds of SSDs, you understand transfer speed of RAM. Imho MT/s just needlessly complicates things because you can't easily compare it to other things in your computer.

 

Since OP was already confused about speed, I didn't see the need to bring latency into the discussion

 

[Zando_]

1 hour ago, Sakkura said:

Sure we do. That's what the numbers are in PC4-19200 for example. That's the other name of DDR4-2400.

Aaaaahhh... so that's what the PC4-xxxxx numbers mean?

[TheBiggestOfBuschemis]

I got a followup question. What do we exactly "write" with RAM? Like when we're writing with RAM, what tasks are we exactly performing?

[Sakkura]

1 hour ago, TheBiggestOfBuschemis said:

I got a followup question. What do we exactly "write" with RAM? Like when we're writing with RAM, what tasks are we exactly performing?

Essentially charging or draining a capacitor in each memory cell.