Original Link: http://www.anandtech.com/show/1273




With the upcoming Intel Grantsdale and Alderwood chipsets will come the first appearance of DDR2 memory and a new CPU socket 775. While the boards are not here yet, the memory is! Kingston is the first to announce shipments of next-generation 533Mhz DDR2 memory, and while it is too early to report test results in unreleased chipsets, we can show you what DDR2 actually looks like and discuss the features and specifications.

Cebit 2004 is in full swing in Germany, and Kingston is showing their recently announced DDR2 modules. While specifications for DDR2 have been available for quite a while, this is our first chance to take a closer look at shipping DDR2 modules.



New DDR2 is at the top of the picture and current DDR is at the bottom. DDR and DDR2 are exactly the same width, which will certainly generate some confusion at first. You can see that DDR2 has a denser 240-pin edge connector, while current DDR uses a 184-pin connector. If you look closely, you can see the notch is in a different location on DDR2.



The relocated notch is to prevent inserting DDR2 accidentally into boards designed for DDR. With voltage for DDR2 set at 1.8V, it would not be a good idea to mount DDR2 in a DDR socket designed for 2.5V.



DDR2 is a standard developed by JEDEC, which is the standards organization for the memory industry. Since the standard is published, there are already established speeds and naming conventions for DDR2 memory.




Basic Features: Kingston DDR2 Memory

The biggest surprise with the new Kingston DDR2 is its introduction as an addition to the Value RAM family.



The shipping DDR2 512MB DIMMs are single-sided 533MHz modules. Kingston has also announced 2GB kits (2 x 1GB) at the same timings as the SS 512MB DIMMs. 512MB kits (2 x 256MB), singles of all 3 densities, have also been announced, and DDR400 speed modules were also announced.



Click to enlarge.


Initially, we will see 1GB (2 x 512MB) DDR2 kits in 533MHz speed. We suspect that market acceptance, pricing, and competition will determine how fast the other densities will appear in the market. The latency and memory timings for the first DDR533 chips is specified as 4-4-4. These look like slow timings for those accustomed to DDR timings, but they are only part of the equation with DDR2. The JEDEC standard for DDR2 is CAS Latencies of 3, 4, and 5. The wider bandwidth and 4-bit prefetch (up from 2-bit in DDR) will improve memory performance. So will the On-Die Termination (ODT) that is used with DDR2 FBGA memory chips; ODT is supposed to reduce signal transmission errors, which improves timing efficiency in DDR2 memory. The point is that while DDR2 is similar to DDR, there are enough differences that memory timings are not directly comparable. Early tests show roughly equivalent performance of DDR2 and DDR with tremendous potential for future memory performance gains. More information on expected performance of DDR2 is available at AT News Update: DDR2 Memory Performance.




Memory Chips: Kingston DDR2 Memory

Another major difference in DDR2 is the use of FBGA (Fine Ball Grid Array) memory chips instead of the current TSOP package.



We recently reviewed Kingmax DDR memory, which uses BGA memory chips, but every other DDR memory that we have tested uses TSOP chips. FBGA offers the same advantages as BGA with shorter traces/better signal integrity, thinner packaging, and better heat dissipation/cooler operation. FBGA just increases the density of the connections.



Kingston uses Elpida FBGA chips in their DDR2-533 modules.

Since the same chips can apparently be used in any DDR533 configuration from 256MB to 1GB per DIMM, then pricing and demand will certainly determine what you will see in the market. Kingston Data Sheets state that DIMMs up to 4GB will be available in DDR2. We expect to see 1GB DIMMs rather quickly, but 4GB DIMMs will only come when higher density FBGA chips become available. One of the potential advantages of DDR2 is certainly the greater capacity of DDR2 DIMMs, allowing more memory in fewer DIMM slots.




Our Take

With all the rumor and speculation about the problems getting DDR2 out the door, it's reassuring to see the world's largest memory manufacturer announcing and shipping DDR2 DIMMs. We're looking forward to reporting how Kingston DDR2 actually performs when the boards and processors are officially announced. At least the holdup now with Intel's Socket 775 should not be the availability of DDR2 memory for the new boards. The early Kingston DDR2 modules are 512MB, but expect to quickly see 1GB DIMMs for sale as the price drops. Kingston is showing a full line of DDR2 modules, and the additional DDR2 offerings will show up quickly if the market for DDR2 takes off. If it develops slowly, as many expect, you will likely wait a while for additional DDR2 memory options.
With DDR2 widely expected to debut at about double the price of DDR, we are anxious to see how fast DDR2 will drop in price - to DDR levels. Much of that depends on how fast DDR2 is adopted by customers. As we reported in our CES coverage in January, almost all the board makers plan to ship Alderwood boards with DDR2 capabilities. Alderwood is the replacement for the 875 chipset, so this high end chipset will likely sell in smaller numbers than the Grantsdale chipset, which will replace the mainstream Intel 865 chipset. This is where the "what-if's" come in because almost every motherboard maker, except Intel, told us they planned to ship Grantsdale with DDR DIMM sockets instead of the DDR2 sockets that it also supports.

We are now hearing talk of Grantsdale boards with dual memory capabilities, and also Grantsdale with DDR2 from other motherboard manufacturers. It will be interesting to see at launch how much Intel has influenced the designs for Grantsdale motherboards from other motherboard manufacturers. Will shipping Grantsdale boards actually be mostly DDR, as we were told to expect in January, or will there be more DDR2 Grantsdale motherboards?

Early reports are that DDR2 performs about the same as current DDR, but with a lot of promise for future performance improvements. With AMD's Socket 939 coming about the same time as Intel 775 - and using dual-channel DDR, not DDR2 - there have to be some real advantages to the latest technology for customers to buy. Unless Alderwood or DDR2 offers significant performance advantages, DDR2 acceptance will come slowly. Customers will move to DDR2 only when it performs better than DDR, or performs the same and costs the same, or when it is the only memory choice available for features they want on Alderwood or Grantsdale. They won't buy just because DDR2 is new or even if it performs a little better at a much higher price. Certainly, Rambus proved that Computer Enthusiasts will not buy at any price.

Congratulations to Kingston for getting DDR2 out the door, even in limited quantities, weeks before DDR2 boards are officially available. This is a good sign of things to come. More information about Kingston DDR2 memory is available at the Kingston website.

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