D D R 4 W H I T E PA P E R
D D R 4 W H I T E PA P E R 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.
D D R 4 W H I T E PA P E R Figure 1: Operating voltage of DDR standards. DDR3 was introduced in 2007, and at the time, DDR2’s effective 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.
D D R 4 W H I T E PA P E R What is DDR4? 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.
D D R 4 W H I T E PA P E R DDR4 in Detail As previously mentioned, the primary benefits of DDR4 are increased bandwidth, a reduction in power consumption, increased density, and improved reliability. Increased Bandwidth While DDR3 kits are available all the way up to 3000MHz, JEDEC only specifies operating speeds up to 2133MHz. Scaling beyond that requires exceptionally high performance ICs, making higher speeds harder and harder to obtain.
D D R 4 W H I T E PA P E R Reduced Power Consumption Power consumption is improved in multiple ways. First, there’s a baseline 20% reduction in the voltage required to operate DDR4. While DDR3 requires 1.5V and DDR3L reduced this requirement to 1.35V, DDR4 starts at 1.2V and is expected to receive a lower specification in the future that further decreases operating power. Beyond that, DDR4 introduces additional power-saving technologies.
D D R 4 W H I T E PA P E R Figure 5: Maximum mainstream module size. Some quick math illustrates the increase in capacity: Sixteen of DDR3’s common 4Gb ICs running in dual rank operation equals 64Gb (16 ICs * 4Gb IC), resulting in DDR3’s signature 8GB DIMM (64Gb / 8). However, DDR4 allows for 8Gb ICs and larger; sixteen of DDR4’s 8Gb ICs running in dual rank operation equals 128Gb (16 ICs * 8Gb IC), resulting in a DDR4 DIMM density of a healthy 16GB (128Gb / 8).
D D R 4 W H I T E PA P E R Conclusion Much like each memory technology transition that preceded it, DDR4’s value upon introduction may seem nebulous compared to the incumbent DDR3. DDR2 operating at the same frequency as mainstream DDR was slightly slower, DDR3 had the same issue with DDR2, and DDR4 will have the same issue with DDR3. This is expected; each transition meant slightly looser timings.
