News on DDR5 ram

  • Thread starter Deleted member 41971
  • Start date

Ash_

Master Poster
Christ... CL40! 4800MHZ at CAS latency 40.
Imagine 6800mhz, could reach triple digits 🤣
 

Scott

Behold The Ford Mondeo
Moderator
2023 is going to be the year I think. DDR5 and Zen4, March 2023. DDR5 will likely be in use a fair bit before that but I don't think it will be at a state of readiness.
 
D

Deleted member 41971

Guest
 
D

Deleted member 41971

Guest
 

Scott

Behold The Ford Mondeo
Moderator
DDR4 - 3200MHz CL16-18-18 - 16/16 = 10ns latency

DDR5 - 4800MHz CL40-40-40 - 40/2.4 = 16.666ns latency

DDR5 - 7200MHz CL36-44-44 - 36/3.6 = 10ns latency

Still not there until the timings come under check. I have absolutely no doubt they will perform better due to other characteristics but that timing is WAY slow.
 

sck451

MOST VALUED CONTRIBUTOR
DDR4 - 3200MHz CL16-18-18 - 16/16 = 10ns latency

DDR5 - 4800MHz CL40-40-40 - 40/2.4 = 16.666ns latency

DDR5 - 7200MHz CL36-44-44 - 36/3.6 = 10ns latency

Still not there until the timings come under check. I have absolutely no doubt they will perform better due to other characteristics but that timing is WAY slow.
At least it's RGB though.
 

NoddyPirate

Grand Master
DDR4 - 3200MHz CL16-18-18 - 16/16 = 10ns latency

DDR5 - 4800MHz CL40-40-40 - 40/2.4 = 16.666ns latency

DDR5 - 7200MHz CL36-44-44 - 36/3.6 = 10ns latency

Still not there until the timings come under check. I have absolutely no doubt they will perform better due to other characteristics but that timing is WAY slow.
CL is only ever part of the story as you indicate @Scott - Typical historical umbers: (obviously selected to make a point :) - but still quite indicative of how things have changed over the years......)

DDR - 400 MHz @ CL2 = 10 ns
DDR2 - 800 MHz @ CL4 - 10 ns
DDR3 - 1600 MHz @ CL8 = 10 ns
DDR4 - 3200 MHz @ CL15 = 10 ns
DDR5 - 7200 MHz @ CL36 = 10 ns

Even taking a less deliberate selection of speeds and latencies to mine above, it's actually quite amazing when you look at it to see that while the speed has increased steadily, the real latency has varied very little over the decades. Yet RAM has performed better and better with each iteration.

So I think you are right that it will be other characteristic that will see the performance benefit for DDR5 - from the RAM end but also from the Processor interface point of view also. The Bandwidth of RAM - which is independent of CL values - has increased from 1.6 GB/s with DDR to 25+ GB/s with DDR4 and a promised 50+ GB/s with DDR5.

So I think we'll see a decent improvement - the real latency is a tempting comparison, but it can be a somewhat misleading way of comparing DDR versions, and even for comparing DIMMs in the same DDR class on occasion too.....
 

Scott

Behold The Ford Mondeo
Moderator
CL is only ever part of the story as you indicate @Scott - Typical historical umbers: (obviously selected to make a point :) - but still quite indicative of how things have changed over the years......)

DDR - 400 MHz @ CL2 = 10 ns
DDR2 - 800 MHz @ CL4 - 10 ns
DDR3 - 1600 MHz @ CL8 = 10 ns
DDR4 - 3200 MHz @ CL15 = 10 ns
DDR5 - 7200 MHz @ CL36 = 10 ns

Even taking a less deliberate selection of speeds and latencies to mine above, it's actually quite amazing when you look at it to see that while the speed has increased steadily, the real latency has varied very little over the decades. Yet RAM has performed better and better with each iteration.

So I think you are right that it will be other characteristic that will see the performance benefit for DDR5 - from the RAM end but also from the Processor interface point of view also. The Bandwidth of RAM - which is independent of CL values - has increased from 1.6 GB/s with DDR to 25+ GB/s with DDR4 and a promised 50+ GB/s with DDR5.

So I think we'll see a decent improvement - the real latency is a tempting comparison, but it can be a somewhat misleading way of comparing DDR versions, and even for comparing DIMMs in the same DDR class on occasion too.....

It will definitely get there when the latencies come down, but the first iteration is not going to see me opening my wallet. It'll be at least a year into the process before we see some proper benefits. The numbers you have posted are mature numbers, save for the DDR5.

The DDR3 to DDR4 transition would define that for me. DDR4 at the beginning was ITRO CL20 IIRC and the frequencies were around the 2400Mhz mark (for the expensive stuff, the cheaper stuff was around 1600mhz with DDR3 coming in around 800 at the start). At that time, the mature DDR3 (1600Mhz of CL8) was performing very similarly to the DDR4. We didn't recommend switching on PCS right away either, as it was pointless unless the platform being chosen had future potential (AM4).

When you look at those original(ish) numbers...

DDR3 - 800Mhz @ CL11 = 27.5ns
DDR4 - 1600mhz @ CL20 = 25ns
DDR5 - 4800mhz @ CL40 = 16.7ns

You can see the dramatic improvement on the DDR5 RAM from the above. The difficulty comes from the maturity point of the competing DDR4...... which is going to be like for like comparable to what you can afford.

Ain't nobody gonna be purchasing 7200MHz of CL36 that hasn't had a lottery win.

With that in mind, I think you will find that the initial release of DDR5 will be very much meh, as they always are. That won't stop the shock, surprise and awe at how "bad" DDR5 is when the reviews hit (#clickbait). There will be at least one very un-surprised gent wafting around this forum though ;)
 

NoddyPirate

Grand Master
It will definitely get there when the latencies come down, but the first iteration is not going to see me opening my wallet. It'll be at least a year into the process before we see some proper benefits. The numbers you have posted are mature numbers, save for the DDR5.

The DDR3 to DDR4 transition would define that for me. DDR4 at the beginning was ITRO CL20 IIRC and the frequencies were around the 2400Mhz mark (for the expensive stuff, the cheaper stuff was around 1600mhz with DDR3 coming in around 800 at the start). At that time, the mature DDR3 (1600Mhz of CL8) was performing very similarly to the DDR4. We didn't recommend switching on PCS right away either, as it was pointless unless the platform being chosen had future potential (AM4).

When you look at those original(ish) numbers...

DDR3 - 800Mhz @ CL11 = 27.5ns
DDR4 - 1600mhz @ CL20 = 25ns
DDR5 - 4800mhz @ CL40 = 16.7ns

You can see the dramatic improvement on the DDR5 RAM from the above. The difficulty comes from the maturity point of the competing DDR4...... which is going to be like for like comparable to what you can afford.

Ain't nobody gonna be purchasing 7200MHz of CL36 that hasn't had a lottery win.

With that in mind, I think you will find that the initial release of DDR5 will be very much meh, as they always are. That won't stop the shock, surprise and awe at how "bad" DDR5 is when the reviews hit (#clickbait). There will be at least one very un-surprised gent wafting around this forum though ;)
With you in all that Scott - and you make a good point about maturity - if DDR5’s opening gambit is CL 36 then things will only get better surely. Although I’m not sure we’ll see 7200 MHz and CL15 necessarily either!

At least DDR5 appears it will have the same pin out as DDR4 and might leave the possibility of having a choice - rather than being forced into DDR5 because it’s all your new motherboard might support - BIOS will determine that I guess.

Still, I think the point also is that 7200MHz @ CL36 is not the same as 400 MHz @ CL2 - there is a lot more involved than true latency. ‘Twill be an interesting thing to watch it all develop as you say.....
 

Scott

Behold The Ford Mondeo
Moderator
Still, I think the point also is that 7200MHz @ CL36 is not the same as 400 MHz @ CL2 - there is a lot more involved than true latency. ‘Twill be an interesting thing to watch it all develop as you say.....

Like for like I believe it is, I can't think why it wouldn't be as the other latencies scale similarly, however there are other changes..... such as the burst length increasing to 16 bits. I believe that means it shoots 16 arrows at once, instead of 8, which may double some sort of output.

Crucial did a white paper on it that I read a wee while back. It was interesting but fairly high level so didn't go into particularly nice detail.

I guess my simplified point is that performance per £ is likely to be on par, or maybe even less than, with DDR4 for a while.
 
Top