STANDARDISATION
What exactly are JEDEC’s standards? And
why are they necessary? Well, the biggest
reason they exist is to ensure consumers
have a non-convoluted platform. They also
ensure that motherboard manufacturers
don’t have to design four different types of
motherboard, just because Corsair has its
own connection standard, HyperX another,
and G.Skill a slightly different variant. You
get the picture. Think of it like USB, but for
memory. The biggy is that all 300 members
can pool their resources to accelerate
technological development, without any one
of them getting a competitive edge, and
saving them time and money in the process.
It’s worth noting that JEDEC’s standardsare on the fairly conservative side of things
when it comes to memory frequency (after
all, they’re designed to work with
everything from desktops to servers and
supercomputers), and DDR5 has yet to be
clarified in its entirety just yet, but you can
see from the table below the standards that
each manufacturer has to adhere to.Standard Name Data Rate (MT/s) Module Name CAS Latency (ns) Real Latency (ns)DDR4-1600J 1,600 PC4-1600 10 12.50DDR4-1600K 1,600 PC4-1600 11 13.75DDR4-1600L 1,600 PC4-1600 12 15.00DDR4-1866L 1,866 PC4-1866 12 12.86DDR4-1866M 1,866 PC4-1866 13 13.93DDR4-1866N 1,866 PC4-1866 14 15.01DDR4-2133N 2,133 PC4-2133 14 13.13DDR4-2133P 2,133 PC4-2133 15 14.06DDR4-2133R 2,133 PC4-2133 16 15.00DDR4-2400P 2,400 PC4-2400 15 12.50DDR4-2400R 2,400 PC4-2400 16 13.33DDR4-2400U 2, 400 PC4-2400 18 15.00JEDEC is poised to announce the next-gen memory
standard (DDR5) later this year, and has confirmed a few
details for us: “DDR5 will offer improved performance,
with greater power efficiency compared to previous
generation DRAM technologies. As planned, DDR5 will
provide double the bandwidth, and density over DDR4,
along with delivering improved channel efficiency.”
That’s exciting, if only for the fact that power
consumption should drop – DDR3 sat at 1.5V and DDR4
at 1.2V, so it’s likely we’ll see DDR5 at 1.0V or lower. The
doubling of density means we’ll likely see mobos double
in max capacity, too, with mainstream platforms maxing
out at 128GB, and high-end desktops hitting a 256GB
limit. Expect initial MT/s figures to hit around
4,133MT/s, with latencies at 27ns if not more. However,
it’s unlikely to come into production until late 2019.THE FUTURE
CHANNEL BANDWIDTH
What is channel bandwidth and how does it
affect memory? Think of it as the maximum
amount of data that can be transferred at any
one time between your system and the
memory installed. It’s calculated by using
MT/s, the width of the memory bus, and the
number of memory channels your system
supports. So, for a typical Ryzen 7 1800X
system, featuring 16GB (2x 8GB) of 3,200MT/s
DDR4, it’s something like this:
3,200,000,000 (3,200MT/s) x 64 (64-bit
bus) x 2 (dual-channel) = 409.6 billion bits per
second, or 51,200MB/s ,or 51.2GB/s.
That’s the absolute maximum amount of
data the system could transfer between the
memory and the processor at any given time,
before bottlenecking. If you were to use a 4x
4GB kit on your dual-channel board,
bandwidth wouldn’t increase, because the
processor can still only read and write from
two memory channels at a time (thus the
dual-channel spec), despite the fact that you
have four DIMMs installed. On the flip side,
installing just one DIMM will cut that figure
in half.
It’s worth noting that for most applications,
dual-channel memory kits provide you with
more than enough bandwidth for everything
you want to do on your desktop. However, for
applications that manipulate massive data sets,
textures, and more, an increase in channel
support can eliminate potential bottlenecks,
because more powerful processors become
more capable at manipulating larger data sets.
4K, 5K, and 8K video editing in After Effects,
for instance, benefits greatly from having
access to both a larger memory capacity and
increased memory bandwidth, thanks to
quad-channel support. Ultimately, you need to
work out exactly how much strain you’ll be
placing on your machine and where
bottlenecks could potentially occur.Feature
Memory Matters
JEDEC STANDARD DDR4 MODULE