Regarding RAM speed - DDR4 vs DDR5
Posted by Sylvi-Fisthaug@reddit | buildapc | View on Reddit | 6 comments
I read somewhere on the great internet once when DDR5 was completely new, it wasn't really faster than DDR4 in many cases. This alluding to frequenzy in MHz vs latency (CLxx)
What I read was that a 6000 MHz CL40 stick was slower than a 3000 MHz CL18 stick, due to the latency having such an impact on total ram speed.
Is this true? I hope I explained it well enough.
Emerald_Flame@reddit
Depends on what you're measuring by.
If you're measuring latency, then yes, generally when a new generation of DDR launches, it's slightly slower than the previous generation. But as time goes on, and things get dialed in over time, that gap gets closed.
Generally speaking most ram ends up in the ballpark of 10ns latency. And that 10ns is more or less that fastest you'll see. Every once in a while you might see something hit 9ns. But once you're around that 10ns mark, your limiting factor becomes the speed of electricity and the length of the traces that connect the socket to the RAM slots.
When a new generation first starts out, it's common to see things with a latency of ~12-13ns. But generally within a handful of product refreshes it comes back down to that 10ns range. The gold standard right now is more or less 6000MT/s CL30, which is 10ns latency.
Now if you're talking about bandwidth. DDR5 was faster basically right out of the gate. The bandwidth of RAM is largely tied to the clockspeed, and the latency doesn't really matter there. Since DDR5 has dramatically higher clock speeds, it has more bandwidth.
Sylvi-Fisthaug@reddit (OP)
Thanks!
Gazpacho_Catapult@reddit
The point on new RAM isn't day 1 performance, it's room to grow. DDR5 has significantly higher possible bandwidth, as well as other QoL improvements that make it objectively superior to DDR4.
The reason this whole "DDR4 bEttEr" arugment got circulated so heavily was A) click-baiters, B) economy of scale favoring DDR4 and C) the release coinciding with the COVID silicon shortage and greater demands on motherboard specs inflating the cost of builds using DDR5.
If you want a really cheap build, DDR4 is fine. If you won't a modern build, DDR5 is objectively superior now.
jfriend00@reddit
And, frankly DDR5 is probably starting to get the economy of scale benefit since all current generation processors require it.
TheeAaron@reddit
DDR4 CL14 4000 still has less latency than most DDR5 kits
GeraltForOverwatch@reddit
That usually happen with new DDR specs but as it matures it leaves the old one behind. Happened with DDR4 as well, which now are mature enough to use 3600MT/s C16 without much fuss.
Plus newer CPUs just dont support the older spec, like AM5 doesn't work with DDR4.
If you're buying now it's a matter of budget. Low budget, stick with DDR4. At the mid-end you should already be going for DDR5, like Ryzen 7600 builds.