Crucial CT25664AC800 2 GB DDR2 800 MHz (PC2-6400) CL6 SODIMM 200-Pin Memory

Product Information

Some manufacturers label their DDR2 modules as PC2-4300, PC2-5400 or PC2-8600 instead of the respective names suggested by JEDEC. At least one manufacturer has reported this reflects successful testing at a higher-than-standard data rate [9] whilst others simply round up for the name. Currently there are two standards for these various DIMM types: DDR (Double Data Rate) and DDR2 (Double Data Rate2). The DDR2 is essentially an upgraded version of the DDR standard that allows for memory modules with lower power consumption, greater heat dissipation, increased speed capabilities, larger memory capacities, and increased performance. For use in computers, DDR2 SDRAM is supplied in DIMMs with 240 pins and a single locating notch. Laptop DDR2 SO-DIMMs have 200 pins and often come identified by an additional S in their designation. DIMMs are identified by their peak transfer capacity (often called bandwidth).

SO-DIMM vs DIMM—In this section, you learn the differences between memory modules made for desktop and those made for laptop computers.

Where Are SODIMMs Used?

According to JEDEC [5] the maximum recommended voltage is 1.9 volts and should be considered the absolute maximum when memory stability is an issue (such as in servers or other mission critical devices). In addition, JEDEC states that memory modules must withstand up to 2.3 volts before incurring permanent damage (although they may not actually function correctly at that level). RAM Types—This section provides the information you need to understand memory chip and module types and how some types of memory are designed to correct memory errors. Variety of Capacities and Speeds: SODIMMs are available in a range of capacities and speeds, allowing users to choose the memory configuration that best meets their needs. There’s DDR4, DDR5, and their predecessors. These are the types of memory modules that define how the particular type of module will perform in terms of throughput, power consumption, latency, etc. Installing Memory—Laptops and desktops differ in how memory is installed, as you learn in this section. Foundation Topics Memory Upgrade Considerations

Whether the system requires or supports multi-channel memory (two or more identical memory modules accessed together instead of one at a time)—Dual-channel memory, triple-channel memory, and quad-channel memory are accessed in an interleaved manner to improve memory latency (the time required between memory accesses). As a result, systems running dual-channel memory offer faster memory performance than systems running single-channel memory. Intel introduced triple-channel memory (which runs even faster than dual-channel memory) with its Core i7 processor. Quad-channel memory, available on some high-performance Intel desktop and server platforms and AMD server platforms, is even faster. Almost all of these systems can run (albeit with reduced performance) if non-identical memory modules are used. Razak Mohammed Ali. "DDR2 SDRAM interfaces for next-gen systems" (PDF). Electronic Engineering Times. Archived from the original (PDF) on 2007-09-26.

Capacity Issues

DDR SODIMM: The original DDR (Double Data Rate) SODIMM, providing improved data rate over earlier SDRAM SODIMMs.