Corsair CMK32GX4M4A2400C14B Fascicule

3

 
DDR4 is a new memory standard designed to eventually replace DDR3. While it’s true that 
when running at the JEDEC specified speeds of 2133MHz and 2400MHz DDR4’s higher 
latencies may produce slightly lower performance clock-for-clock than DDR3, DDR4 is 
designed to reliably run at much higher speeds that more than offset the increased latency. 
In virtually every way, DDR4 is superior to DDR3: it’s capable of being much faster, more 
efficient, more scalable, and even more reliable. As for cost, much like the transitions to 
DDR, DDR2, and DDR3, DDR4 will become progressively cheaper as economies of scale 
take effect. 
 
Physically, a DDR4 module, or DIMM, is very similar to a DDR3 DIMM. DDR4 can use a 
slightly taller printed circuit board and ups the pin count from DDR2 and DDR3’s 240 pins 
to 288. The key notch (to ensure the DIMM is not improperly installed) is also in a different 
place, and the overall shape of the connector has a slight “V” contour to aid installation. 
 
Architecturally, DDR4 is designed to operate at higher speeds and capacities with lower 
voltage and adds reliability features not present in DDR3.

 
When DDR4 is introduced, the initial 2133MHz and 2400MHz speeds will be accompanied 
by another increase in latency, just as each previous memory technology transition has 
been. These speeds are essentially the top of the ladder for DDR3, though; while DDR3 kits 
can be obtained at speeds as high as 3200MHz, ICs capable of performing at those levels 
are extremely rare. Meanwhile, DDR4 is expected to scale well beyond 3200MHz. 
 
What DDR4 offers is scalability for the future: individual DIMM densities start at 4GB and 
8GB and are expected to scale to 16GB in 2015. Bandwidth is also capable of scaling up 
tremendously. 2666MHz DDR3 isn’t especially common right now; it operates outside 
of JEDEC spec and requires carefully selected ICs, yet already situations exist that 
demonstrate a need for increased bandwidth beyond that speed. DDR4 comes out of the 
gate at 2400MHz, with 2666MHz, 2800MHz, and 3000MHz SKUs already planned.

 

Figure 3: DDR bandwidth growth over time.

Finally, DDR4 operates at a nominal 1.2V and scales up to 1.35V, a reduction in operating 
power from DDR3’s 1.5V standard and 1.65V mainstream high performance spec. Power 
efficiency has become increasingly important with each subsequent generation of CPU and 
GPU architecture from Intel, AMD, and NVIDIA, and DDR4 helps to enable that.