7 ms·

Samsung Announces 512GB DDR5 Memory That Is Twice as Fast as DDR4

76 points by kjhughes 6y ago

hedora 6y ago
No mention of latency. Presumably that means this will be higher latency than DDR4 (following recent trends to simultaneously increase DRAM bandwidth and latency).
- api 6y ago
  It is a bit of a trade-off. For desktops and other personal devices you usually want lower latency. For servers and HPC you often want higher bandwidth.
- throwaway888abc 6y ago
  Bw/latency comparison https://www.anandtech.com/show/16143/insights-into-ddr5-subtimings-and-latencies https://www.anandtech.com/show/16143/insights-into-ddr5-subt...
  - gruez 6y ago
    It's worth noting there's a disconnect between the JEDEC standard latencies and what's actually available. It lists the DDR4 latencies at around 13-14ns but 10ns latency kits can be bought without paying a significant premium[1]. [1] https://pcpartpicker.com/products/memory/#Z=32768002&sort=price&U=4 https://pcpartpicker.com/products/memory/#Z=32768002&sort=pr...
    - deleted 6y ago
      [deleted]
- zlynx 6y ago
  Latency often does increase with new generations of RAM. But remember to compensate latency cycle counts with the faster cycles of higher speed RAM. Often the absolute time in nanoseconds hasn't changed as much as the cycle count numbers make it seem.
- xiphias2 6y ago
  Isn't the biggest problem with SSD latency generally that paralell reading / writing is not used within software that was optimized for hard disk?
peter_d_sherman 6y ago
Random Idea: If we think about it, computers today have a limited number of RAM expansion slots, even on server motherboards, the number of RAM slots might be limited to say, 32. So, I'm wondering (and maybe something like this already exists) what if RAM could be placed at the end of a high-speed serial cable of some sort. Like Firewire, Ethernet, Fast USB, or some kind of LVDS high-speed data serial cable... Now, this RAM (because it would allow for long cable sizes, because we'd like to connect more of it to a PC, and thus the serial cable speed would be a bit reduced due to length) would not be intended as System RAM -- but more like a faster-than-SSD hard drive -- although perhaps it could be used as System RAM, just as slightly slower System RAM... Note To Future Self: Look into the various ways that RAM can be connected via high-speed serial links (also, in the future, such links might include optical fiber...). So, high speed serial links AND optical fiber...
- GrumpyYoungMan 6y ago
  It's been tried but never achieved any significant commercial success. https://en.wikipedia.org/wiki/Texas_Memory_Systems https://en.wikipedia.org/wiki/Texas_Memory_Systems https://en.wikipedia.org/wiki/I-RAM https://en.wikipedia.org/wiki/I-RAM https://en.wikipedia.org/wiki/HyperOs_HyperDrive https://en.wikipedia.org/wiki/HyperOs_HyperDrive
- garaetjjte 6y ago
  > Look into the various ways that RAM can be connected via high-speed serial links https://www.devever.net/~hl/omi https://www.devever.net/~hl/omi
- meepmorp 6y ago
  Look at CXL for what industry is doing in that general direction, and Gen-Z which kinda sorta extends the general idea beyond a box/rack with pooled accelerators and memory Edit: and IBM’s CAPI
  - splistud 6y ago
    This plus NAND is where we're headed I believe
ksec 6y ago
I didn't look too deeply into DDR5 but I am going to guess 512GB per DIMM will be using half channel per group of DRAM Rank. Which I assume will only allow 8 DIMM per socket on a 16 Memory Channel CPU at a maximum of 4TB Memory per Socket.
- henriquez 6y ago
  Out of curiosity, what CPUs support 16 memory channels?
  - ksec 6y ago
    In terms of DDR4, AFAIK none. But in the context of DDR5, each DIMM is now Dual Channel.
MR4D 6y ago
Am I missing something here? - The speed of this is 7,200 Mbps (lowercase "b"). - The speed of a fast SSD is 7,000 MBps (uppercase "B"). Why am I paying for tons of ram to cache anymore? (I'm ignoring wear & tear for this question.) Referenced SSD speed source from here: https://www.gamingpcbuilder.com/best-m-2-nvme-ssd/ https://www.gamingpcbuilder.com/best-m-2-nvme-ssd/ -------- EDIT: found the answer here: "Samsung's latest module would deliver around 57.6 GB/s transfer speeds on a single channel" https://www.engadget.com/samsung-unveils-a-512-gb-ddr-5-ram-module-102447443.html https://www.engadget.com/samsung-unveils-a-512-gb-ddr-5-ram-...
- tkinom 6y ago
  On SSD latency on write is much longer and it is block (512B to 1K) read/write only. DDR is random per byte/word.
z-10 6y ago
With such memory capacity it seems we now can store entire operating system in ram. While we at it we can get rid of a file system since everything is in ram anyways
rasz 6y ago
> Twice as Fast twice the transfer speed, same latency (if we are lucky). For reference https://en.wikipedia.org/wiki/CAS_latency https://en.wikipedia.org/wiki/CAS_latency https://www.crucial.com/articles/about-memory/difference-between-speed-and-latency https://www.crucial.com/articles/about-memory/difference-bet...

76 points by kjhughes 6y ago

No mention of latency. Presumably that means this will be higher latency than DDR4 (following recent trends to simultaneously increase DRAM bandwidth and latency).

api 6y ago
It is a bit of a trade-off. For desktops and other personal devices you usually want lower latency. For servers and HPC you often want higher bandwidth.
throwaway888abc 6y ago
Bw/latency comparison https://www.anandtech.com/show/16143/insights-into-ddr5-subtimings-and-latencies https://www.anandtech.com/show/16143/insights-into-ddr5-subt...
- gruez 6y ago
  It's worth noting there's a disconnect between the JEDEC standard latencies and what's actually available. It lists the DDR4 latencies at around 13-14ns but 10ns latency kits can be bought without paying a significant premium[1]. [1] https://pcpartpicker.com/products/memory/#Z=32768002&sort=price&U=4 https://pcpartpicker.com/products/memory/#Z=32768002&sort=pr...
  - deleted 6y ago
    [deleted]
zlynx 6y ago
Latency often does increase with new generations of RAM. But remember to compensate latency cycle counts with the faster cycles of higher speed RAM. Often the absolute time in nanoseconds hasn't changed as much as the cycle count numbers make it seem.
xiphias2 6y ago
Isn't the biggest problem with SSD latency generally that paralell reading / writing is not used within software that was optimized for hard disk?

peter_d_sherman 6y ago

Random Idea: If we think about it, computers today have a limited number of RAM expansion slots, even on server motherboards, the number of RAM slots might be limited to say, 32. So, I'm wondering (and maybe something like this already exists) what if RAM could be placed at the end of a high-speed serial cable of some sort. Like Firewire, Ethernet, Fast USB, or some kind of LVDS high-speed data serial cable... Now, this RAM (because it would allow for long cable sizes, because we'd like to connect more of it to a PC, and thus the serial cable speed would be a bit reduced due to length) would not be intended as System RAM -- but more like a faster-than-SSD hard drive -- although perhaps it could be used as System RAM, just as slightly slower System RAM... Note To Future Self: Look into the various ways that RAM can be connected via high-speed serial links (also, in the future, such links might include optical fiber...). So, high speed serial links AND optical fiber...

GrumpyYoungMan 6y ago
It's been tried but never achieved any significant commercial success. https://en.wikipedia.org/wiki/Texas_Memory_Systems https://en.wikipedia.org/wiki/Texas_Memory_Systems https://en.wikipedia.org/wiki/I-RAM https://en.wikipedia.org/wiki/I-RAM https://en.wikipedia.org/wiki/HyperOs_HyperDrive https://en.wikipedia.org/wiki/HyperOs_HyperDrive
garaetjjte 6y ago
> Look into the various ways that RAM can be connected via high-speed serial links https://www.devever.net/~hl/omi https://www.devever.net/~hl/omi
meepmorp 6y ago
Look at CXL for what industry is doing in that general direction, and Gen-Z which kinda sorta extends the general idea beyond a box/rack with pooled accelerators and memory Edit: and IBM’s CAPI
- splistud 6y ago
  This plus NAND is where we're headed I believe

ksec 6y ago

I didn't look too deeply into DDR5 but I am going to guess 512GB per DIMM will be using half channel per group of DRAM Rank. Which I assume will only allow 8 DIMM per socket on a 16 Memory Channel CPU at a maximum of 4TB Memory per Socket.

henriquez 6y ago
Out of curiosity, what CPUs support 16 memory channels?
- ksec 6y ago
  In terms of DDR4, AFAIK none. But in the context of DDR5, each DIMM is now Dual Channel.

MR4D 6y ago

Am I missing something here? - The speed of this is 7,200 Mbps (lowercase "b"). - The speed of a fast SSD is 7,000 MBps (uppercase "B"). Why am I paying for tons of ram to cache anymore? (I'm ignoring wear & tear for this question.) Referenced SSD speed source from here: https://www.gamingpcbuilder.com/best-m-2-nvme-ssd/ https://www.gamingpcbuilder.com/best-m-2-nvme-ssd/ -------- EDIT: found the answer here: "Samsung's latest module would deliver around 57.6 GB/s transfer speeds on a single channel" https://www.engadget.com/samsung-unveils-a-512-gb-ddr-5-ram-module-102447443.html https://www.engadget.com/samsung-unveils-a-512-gb-ddr-5-ram-...

tkinom 6y ago
On SSD latency on write is much longer and it is block (512B to 1K) read/write only. DDR is random per byte/word.

z-10 6y ago

With such memory capacity it seems we now can store entire operating system in ram. While we at it we can get rid of a file system since everything is in ram anyways

rasz 6y ago

> Twice as Fast twice the transfer speed, same latency (if we are lucky). For reference https://en.wikipedia.org/wiki/CAS_latency https://en.wikipedia.org/wiki/CAS_latency https://www.crucial.com/articles/about-memory/difference-between-speed-and-latency https://www.crucial.com/articles/about-memory/difference-bet...