New DDR4 memory to boost tablet, server performance

Expect big performance gains in data centers and on consumer devices

Lucas Mearian
May 15, 2012 (Computerworld)
The upcoming shift from Double Data Rate 3 (DDR3) RAM to its successor, DDR4, will herald in a significant boost in both memory performance and capacity for data center hardware and consumer products alike.
The DDR4 memory standard, which the Joint Electronic Devices Engineering Council (JEDEC) expects to OK this summer, represents a doubling of performance over its predecessor and a reduction in power use by 20% to 40% based on a maximum 1.2 volts of power use.
"It's a fantastic product," said Mike Howard, an analyst with market research firm IHS iSuppli. "Increasing the amount of memory and the bandwidth of that memory is going to have huge implications."
DDR4's significant reduction in power needs means that relatively low-priced DDR memory will, for the first time, be used in mobile products such as ultrabooks and tablets, according to Howard.
Today, mobile devices use low-power DDR (LPDDR) memory, the current iteration of which uses 1.2v of power. The next generation of mobile memory, LPDDR3, will further reduce that power consumption (probably by 35% to 40%), but it will likely cost 40% more than DDR4 memory, said Howard. (LPDDR memory is more expensive to manufacture.)

Designed for servers

The impact that DDR4 will have on the server market could be even greater.
Intel, for example, is planning to start using DDR4 in 2014, but only in server platforms, according to Howard. "Server platforms are the ones really screaming for this stuff, because they need the bandwidth and the lower voltage to reduce their power consumption.
"So while Intel is only supporting DDR4 on their server platforms in 2014, I have a feeling they're going to push it to their compute platforms as well in 2014," Howard continued.
The draft of the DDR4 specification and its key attributes were released last August.
"With DDR4, we're certainly ... seeing some larger power savings advantages with the performance increase," said Todd Farrell, director of technical marketing for Micron's DRAM Solutions Group.
Both Samsung and Micron have announced they're preparing to ship memory modules based on the DDR4 standard. Samsung's memory modules, expected to ship later this year, purport to reduce power use by up to 40%. Both companies are using 30-nanometer circuitry to build their products, their smallest to date.
By employing a new circuit architecture, Samsung said its DDR4 modules will be able to perform operations at speeds of up to 3.2Gbps, compared with today's DDR3 speeds of 1.6Gbps and DDR2's speeds of up to 800Mbps.
Another benefit from the arrival of DDR4 will be greater density and the ability to stack more chips atop one another. Micron's DDR4 memory module is expected to ship next year, but test modules have already shipped to system manufacturers.
"For DDR3, we see stacking going up to four chips (4H), [but] for DDR4 this clearly will go up to eight chips stacked on top of each other (8H), which means that, using a 16Gbit memory [chip], manufacturers will be able to produce 128Gbit memory boards," Farrell said.
Farrell described the jump from DDR3 to DDR4 as greater than any other past DDR memory evolution.
"It's hard to pick just one [attribute]. DDR4 is one of these devices where you're getting a lot of benefits at once. Power reduction is key. But at the same time we're reducing power, we're getting a substantial increase in performance. They kind of go hand in hand," Farrell said.
For example, if you run DDR4 at the same bandwidth as DDR3, you can achieve a 30% to 40% power savings. Running at its maximum bandwidth, which represents a doubling of performance, DDR4 will use the same power as its predecessor.

Does power improvement matter?

Historically, memory power consumption has not been considered a big issue because at the motherboard level, processors were responsible for most of the power use in a system.
"Moving forward, as we see a tremendous amount of power reduction -- especially in tablets -- at that point, if the memory power doesn't reduce with it ... all of a sudden the memory is setting your battery life," Farrell said.
I/O signaling has been improved for added power savings. The I/O uses an "open drain" driver, meaning it only uses power when it writes a zero and not a one at the data bit level. Previous DDR memory used power when writing both zeros and ones.
"Our DRAM controller doesn't drive current to a one," Farrell said.
Another power-saving feature with the DDR4 standard will be a reduction in refreshes. In DDR3 memory boards, refreshes occur periodically -- and more frequently as the temperature of a device rises. DDR4 memory is being tuned to take advantage of mobile device cooling capabilities. For example, as mobile devices like tablets and laptops go into sleep mode, they cool off. As they cool, DDR4 memory modules will refresh less often, thus using less power.
Additionally, DDR4 can be optimized for server use. For example, higher reliability can be configured using a Cyclic Redundancy Check for the data bus to verify the integrity of the memory. The command address bus also has parity built directly into the DRAM module. Traditionally, parity was achieved through the use of a separate register or another chip on a buffer DIMM.

Memory prices plummet, then stabilize

Even as the arrival of DDR4 memory nears, prices for DRAM remain soft, though the market is expected to pick up steam this year.
Last year, IHS iSuppli reported there was an oversupply in the DRAM market as demand came in lower than expected.
ISuppli has released figures showing that DRAM pricing declined to its lowest point at the end of 2010, the latest period for which it has released data. In December 2010, the contract price for a 2GB DDR3 DRAM module stood at $21, less than half the $44.40 the same module cost just six months earlier.
The price dip isn't restricted to DDR3. Pricing for a DDR2 DRAM module dropped to $21.50 in December 2011, down from $38.80 in June 2010, according to iSuppli.
This year, iSuppli said it has a much more optimistic outlook for DRAM prices. "DRAM prices have stabilized (and look to stay firm), and the dynamic of the world economy looks much more positive in 2012," it stated in a report last month.
After seeing major price declines in 2011, memory manufacturers cut output, bringing supply more in line with demand.
"Prices have been essentially flat in the commodity memory market since December, specifically DDR3. It is really weird," Howard said, adding that market consolidation should help firm up memory prices this year.
For example, Japan's Elpida Memory filed for bankruptcy in February. This week reports circulated that Micron is in talks to acquire Elpida.
"So it looks like there is going to be some really meaningful consolidation in the industry, and that's pointing to a much better balance between supply and demand," Howard said. "We're anticipating prices for commodity products increasing in the second half of the year."
 covers storage, disaster recovery and business continuity, financial services infrastructure and health care IT for Computerworld. Follow Lucas on Twitter at Twitter@lucasmearian, or subscribe to Lucas's RSS feed Mearian RSS. His email address


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