SO-DIMM

PC6400 DDR2 SO-DIMM (200 pins)

PC3-10600 DDR3 SO-DIMM (204 pins)

Comparison of 200-pin SO-DIMMs for DDR SDRAM, DDR2 SDRAM and DDR3 SDRAM for laptops PCs

A slot on a mainboard for SO-DIMMs

An SO-DIMM, or small outline dual in-line memory module, is a type of computer memory built using integrated circuits.

SO-DIMMs (also written SODIMMs) are a smaller alternative to a DIMM, being roughly half the size of regular DIMMs. SO-DIMMs are often used in systems that have limited space, such as notebooks, small footprint PCs (such as those with a Mini-ITX motherboard), high-end upgradable office printers, and networking hardware like routers.

Visual identification

Most types of SO-DIMMs can be recognized at a glance by the distinctive notches that “key” them for different applications:^{[citation needed]}

• 100-pin SO-DIMMs have two notches
• 144-pin SO-DIMMs have a single notch near the center
• 200-pin SO-DIMMs have a single notch nearer to one side. The exact location of this notch varies (read below.)
• 204-pin SO-DIMMs (DDR3) have a single notch closer to the center than on 200-pin SO-DIMMs.

Variants of 200-pin SO-DIMMs

The 200-pin SO-DIMM notch is in one of three locations:

• If the notch is located away from the center, it indicates the DDR class of memory.^{[citation needed]}
• When the notch is located slightly closer to the center of the board, it generally (but not always) indicates that the RAM is of the DDR2 type.^{[citation needed]}

These two types of memory are not interchangeable. The different notch locations are designed to prevent cross-installation. Keep this in mind when attempting to visually identify 200-pin SO-DIMM modules.

This variance is designed to prevent coupling of memory and controllers of different DDR generations due to electrical incompatibility. DDR1 SO-DIMMs operate at 2.6 Volts while DDR2 SO-DIMMs operate at 1.8 Volts.

General characteristics

200- and 204-pin SO-DIMMs measure at 6.76 cm in length and a width of 3.175 cm with a maximum total depth of 0.38 cm.

SO-DIMMs are more or less equal in power and voltage rating to DIMMs, and as memory technology moves forward and despite their smaller size, SO-DIMM technology allows for performance speeds as high as the those of the larger DIMMs (clock speeds such as 400 MHz PC-3200, for example, and CAS latency such as 2.0, 2.5, and 3.0) and capacity (512MB, 1GB, etc.).

DDR2 SO-DIMM memory modules commonly have clock speeds from 200 MHz up to 800 MHz PC2-6400.^{[citation needed]}

The latest 204-pin SO-DIMMs can contain DDR3 SDRAM, with specifications such as PC3-6400, PC3-8500, PC3-10600, and PC3-12800.

See also

• DDR SDRAM
• DDR2 SDRAM
• DDR3 SDRAM
• DDR4 SDRAM

External links

• How to Install PC Memory Guides