DDR4 WHITE PAPER
DDR4 WHITE PAPER
Introduction
DDR3 has been with us for a long time, and Corsair has been there pushing the bleeding
edge of performance, cooperating with Intel, AMD, and motherboard manufacturers to
produce the fastest memory consumers can buy. Yet DDR3 is getting long in the tooth
and modern processor architectures are becoming increasingly demanding. When today’s
hardware needs exotic, high-speed, carefully binned memory, it’s time to look to a new
technology.
Introduced in conjunction with Intel’s new high end desktop platform based on their
Haswell-E architecture and the X99 chipset, DDR4 is designed to meet the needs of
present and future platforms. It oers higher performance, lower power consumption,
higher density, increased reliability, and a remarkably forward-thinking design geared for
heretofore unprecedented scaling. In short, DDR4 is the memory technology we need, now
and for tomorrow.
The Demands of Modern Hardware
While Moore’s Law has slowed somewhat for x86 processors, the steady march of progress
in terms of both performance and hardware integration has resulted in a hardware
ecosystem that is very slowly reaching the limits of what can be achieved with DDR3.
Increasingly powerful x86 cores are now being married with substantially powerful graphics
hardware on a single die, boosting the stress placed on the memory bus and raising the
amount of memory bandwidth needed to keep these new integrated processors fed.
With Intel’s Haswell and AMD’s Kaveri architectures, we are seeing more and more
situations where performance can be bottlenecked by a lack of memory bandwidth.
Content creation (CAD, video editing, et al) continues to need as much memory capacity
as possible. Meanwhile, mobile devices (notebooks, tablets) focus more and more on power
eciency. All of this, to say nothing of the ever escalating demands on enterprise and
server hardware, hardware that often requires as much bandwidth and capacity as can be
delivered while needing to reduce power consumption wherever possible.
The demands of current and future hardware and software architectures can be met with
DDR4.
The History of DDR3
To understand DDR4, we need to have at least a working knowledge of the history of
DDR3. With rare exception, introductions of new memory standards operate cyclically.
When the original double data rate (DDR) memory was introduced, users were still working
with SDRAM running at 133MHz, and the benefits of moving to this faster standard were
limited. The outgoing technology will always be more mature and have a better price-toperformance ratio than its successor at time of launch; this was true of the transition from
DDR to DDR2 and again from DDR2 to DDR3.
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DDR4 WHITE PAPER
Figure 1: Operating voltage of DDR standards.
DDR3 was introduced in 2007, and at the time, DDR2’s eective mainstream speed had
standardized at 800MHz with JEDEC’s peak spec at 1066MHz. DDR3’s introductory
speeds were 800MHz and 1066MHz, but performance could actually be slightly lower in
some instances due to higher latency. Yet DDR2 was a mature technology and at its limit;
mainstream DIMM density topped out at 4GB and operating voltage was between 1.8V and
2.5V.
DDR3 was more forward thinking; specified voltage was 1.5V, speeds were designed to
scale well past 1066MHz, and Intel (working with Corsair) created and incorporated the
XMP specification that allowed end users to easily fine tune speeds and timings for high
performance memory. So while DDR2 had a better value proposition when DDR3 launched,
it was quickly eclipsed by the new specification’s headroom.
Figure 2: A history of DDR SDRAM memory speeds.
Seven years later, JEDEC has specified DDR3 speeds all the way up to 2133MHz,
mainstream DIMM density is 8GB (with server DIMMs at 16GB), and an adjoining DDR3L
standard has been adopted that operates at a reduced 1.35V. High performance DDR3 even
exceeds 2133MHz; internal Corsair testing has seen Intel Haswell processors show continued
performance benefits up to 2400MHz, while the GCN-architecture graphics cores powering
AMD’s Kaveri processors are demonstrably bottlenecked even then. While the mainstream
has settled on 1600MHz as the standard speed for DDR3 and Corsair memory continues
to drive speeds well beyond that, it is possible to be performance limited by even exotic
2400MHz memory on current generation hardware. Beyond that speed price can increase
dramatically, reflecting the careful binning of ICs that has to take place to produce those
extremely high speed DIMMs. DDR3 has scaled well beyond the performance of DDR2, but
is now approaching its own limits.
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