Monday, November 02, 2009
DDR3 memory - what happend?
I've just had to buy a new laptop, and wanted something that would last for a good few years, so naturally wanted high speed, low power DDR3 memory. Could I find much? No, really just Dell and Acer.
So this analysis of what happened from Malcolm Penn at Future Horizons is well timed, and an excellent description of how technology does, or doesn't get adopted, and the implications for the embedded market! It looks like my timing is good though as now I have a lovely DDR3 system at a reasonable, not bleeding edge, cost.
Semiconductor Spotlight – DDR3
The DRAM manufacturers as a whole made a combined loss during 2008 of US$20 billion. At the moment memory pricing is firming but semiconductor memories are still plagued by a regular cyclicality of over-capacity and declining ASPs countered by tightening capacity and rising ASPs. However, although improvements are evident in the short term, the longer-term trends are still up for debate. One of the major trends currently under way is the trend to DDR3 memory from the current mainstream DDR2.
DDR, DDR2 and DDR3 are types of SDRAM (Synchronous Dynamic Random Access Memory) and use a clock signal for synchronization. DDR stands for Double Data Rate, meaning that memories from this category transfer two data chunks per clock cycle.
One of the main differences between DDR, DDR2 and DDR3 is the highest transfer rate each generation can achieve. For example, higher speed DDR2-1066 memory operates at a clock rate of 533 MHz. Whilst there is an equivalent DDR3 memory that also operates at this speed, the DDR3-1600 operates with a clock rate of 800MHz. In addition, the internal data path of DDR2 memory is 4 bits whilst DDR3 is 8 bits. DDR3 memories also operate at lower voltages compared to DDR2 memories.
This lower voltage means that DDR3 consumes less power than DDR2 for a given clock rate and lower power is becoming increasingly important for laptops and the general trend of electronic equipment to become ‘greener’.
On the minus side, DDR3 memories have higher latencies than DDR2 memories. This means that DDR3 memories take more clock cycles initially before delivering data compared to DDR2 memories.
The primary benefit of DDR3 is the ability to transfer at twice the data rate of DDR2. DDR3 can operate at higher clock rates than DDR2 and DDR3 memory uses less power for the same clock rate. An emphasis on low power and higher data rates make DDR3 memory a more attractive option provided there is a low premium on price and the motherboards are ‘DDR3 ready’.
The first DDR2's replaced DDR in PCs by Dell during the summer of 2004 and were DDR2-533 specification. Dell has been one of the leaders in new system development and it was expected that that the transition to DDR2 would start getting underway very soon after. However, history showed that the uptake of DDR2 was not a smooth transition with memory manufacturers reverting to DDR and then going back to DDR2. The changeover eventually occurred during early 2006 when DDR2-667 had both a performance and price advantage.
It looks as though history will repeat itself with the transition to DDR3 from DDR2 but perhaps over a shorter time-span. DDR3 has been in gestation since 2005 and has appeared on some motherboards during 2007. Optimistic predictions were made for adoption during early 2008 with predictions of 30 percent or more penetration of DDR3 memory with less than ten percent price difference in price over DDR2 by the end of 2008.
By mid-year 2008 this prediction was looking increasingly unlikely and eventually did not happen. However, the pricing has been altering in favour of DDR3 in the last four months and the percentage of DDR3 has been creeping up to over 20 percent of total PC memory in the first half of this year.
PC OEMs are inexorably price driven and will tend to use the cheapest available memory given comparable performance in mainstream machines. Another factor is, of course, the type of memory the motherboard can take. DDR3 has become more popular since July and, as a consequence, the price for this memory rose as demand increased.
As the DDR3 prices increased, PC manufacturers started to go back to using DDR2 as these were lower in price. However, increased DDR2 demand, in turn, drove up prices. With prices now higher for DDR2, PC OEMs will switch back to DDR3 parts. This cycle will likely continue for the next six months until DDR3 memory becomes the mainstream memory for PCs probably during mid-2010.
The adoption of any new technology is always beset by problems in its introduction and the transition from DDR2 to DDR3 is promising to be no exception. It has been clear for some time that DDR3 memory has had the potential to become the mainstream PC memory but market adoption depends on a careful mix of price and performance with a lot of emphasis on price.
As such we believe DDR3 will really come into its own when the new generation 50nm designs hit the market. This advance will also allow a large increase in die-per-wafer and either an improvement in profitability or a tool to increase market share depending on the individual memory manufacture’s strategy.
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