The DDR2 SD RAM memory module had been launched to the market in summer 2002 and optically it hardly distinguishes from the DDR DIMM memory module. Only with a trained view you will recognize that it has one notch at the bottom side and two notches each on the sides, otherwise the dimensions are equal. The DDR2 SD RAM memory module cannot be built in the common slot for DDR RAM memory modules as the assignment, the notching and the number of pins are different.
From the technical point of view the DDR2 SD RAM memory module is working the same way as the DDR RAM memory module with two signals per pulse with the difference that the I/O buffer of the chip is running with the double pulse frequency. Hereof results another doubling of the data frequency compared to the DDR RAM memory module.
The ?problems? of the DDR2 DS RAM memory modules are the high latencies.
Due to the bad timings the DDR2 SD RAM memory module may lose up to 10% of its actual capability compared to the common DDR RAM memory modules with the same band width.
However the DDR2 SD RAM memory module had been developed for high clock speeds so that this disadvantage is not significant and can be relativized rapidly.
In the following text some further differences are shown:
- FBGA chips (a kind of "base seat" -> 50% smaller chips are possible)
- Manufacturing process in 100 to 130 nm
- Module sizes from 128 MB to 4 GB
- little tension (1.8 volts)
- considerably less power requirement (247 mW compared to 527 mW up to now)
- considerably higher clock speeds are possible
Here the models which are available up to now:
- PC2-3200 / DDR2-400 (internal 100MHz)
- PC2-4300 / DDR2-533 (internal 133MHz)
- PC2-5300 / DDR2-667 (internal 166MHz)
- PC2-6400 / DDR2-800 (internal 200MHz)