In Search of True DDR2 Bleeding Edge Memory
DDR2 Parts Details
Typical module sizes for DDR2 RAM are 512 MB and 1 GB. DIMMs with 256 MB or 2 GB are somewhat harder to find on the market. Uninformed buyers are sure to be confused by the many and varied memory speed designations, shown in the following table.
| Module | Clock | PC |
|---|---|---|
| DDR2-1066 | 533 MHz | PC8000 |
| DDR2-888 | 444 MHz | PC7100 |
| DDR2-800 | 400 MHz | PC6400 |
| DDR2-711 | 355 MHz | PC5700 |
| DDR2-667 | 333 MHz | PC5300 |
| DDR2-533 | 266 MHz | PC4200 |
| DDR2-400 | 200 MHZ | PC3200 |
Additional information about placement of individual memory chips on a module and their organization.
Most memory makers offer precise information about what chips they use in their modules.
The designation: "Chip: 64Mx8" means that individual chips on a module consist of eight 64-megabit memory parts (64 megabits / 8 bits per Byte = 8 MegaBytes or MB = 64 MB total). By extension, each individual chip has a storage capacity of 64 megabits.
The designation: "Module: 128Mx64" indicates that the entire module includes 64 parts, each 128 megabits in size (128 megabits / 8 bits per Byte = 16 MB x 64 parts = 1 GB). If a 1 GB module is composed of 16 individual chips, each chip must therefore have 64 MB of capacity. In this case, we're talking about double-sided modules, because when it comes to large-capacity chips only eight typically fit on each side of a standard memory module.
Typical configurations for desktop DDR2 memory modules are:
| Module Capacity | Sides | Typical Chip Organization |
|---|---|---|
| 256 MB | 1 | 32 MB Chip x 8 |
| 512 MB | 2 | 32 MB Chip x 8 x 2 Sides |
| 512 MB | 1 | 64 MB Chip x 8 |
| 1 GB | 2 | 64 MB Chip x 8 x 2 Sides |
| 1 GB | 1 | 128 MB Chip x 8 |
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