Most types of desktop memory modules use unbuffered memory. However, many servers and some desktop or workstation computers use a type of memory module called registered memory or buffered memory: buffered memory is the term used by the 220-901 exam. Buffered (registered) memory modules contain a register chip that enables the system to remain stable with large amounts of memory installed. The register chip acts as a buffer, which slightly slows down memory access. When it comes to memory, compatibility is important. The memory module type must fit the motherboard; speed must be compatible and the module storage size/combination must match your computer system as well. Apart from the distinctive size and cuts on a module, you can also determine what form factor RAM module is installed on your Windows PC without opening it up. Here is how: Samsung Electronics Announces JEDEC-Compliant 256Mb GDDR2 for 3D Graphics". Samsung Electronics. Samsung. 23 August 2003 . Retrieved 26 June 2019. Single-Sided vs Double-Sided—Learn what these terms mean and how they might affect how much RAM you can install on a particular system.

Double data rate 3 SDRAM (DDR3 SDRAM) Compared to DDR2, DDR3 runs at lower voltages, has twice the internal banks, and most versions run at faster speeds than DDR2. DDR3 also has an eight-bit prefetch bus. As with DDR2 versus DDR, DDR3 has greater latency than DDR2. Typical latency values for mainstream DDR3 memory are CL7 or CL9, compared to CL5 or CL6 for DDR2. Although DDR3 modules also use 240 pins, their layout and keying are different than DDR2, and they cannot be interchanged. DDR4 SODIMM: The latest iteration, providing further improvements in data rate and power efficiency over DDR3 SODIMMs. Figure 4-2 A standard unbuffered module (top) compared to a buffered (registered) module with ECC (bottom).The table below summarises the three common form factors of memory modules used in tech gadgets today: Full-height 288-pin DDR4 DIMMs are slightly taller than their DDR3 counterparts at 1.23 inches (31mm). Similarly, VLP DDR4 DIMMs are also marginally taller than their DDR3 equivalent at nearly 0.74 inches (19mm). [15] A SO-DIMM (pronounced "so-dimm" / ˈ s oʊ d ɪ m/, also spelled " SODIMM") or small outline DIMM, is a smaller alternative to a DIMM, being roughly half the physical size of a regular DIMM. The first SODIMMs had 72 pins and were introduced by JEDEC in 1997. [7] [8] [9] Before its introduction, most laptops would use propietary RAM modules which were expensive and hard to find. [7] [10] Double data rate 2 SDRAM (DDR2 SDRAM) is the successor to DDR SDRAM. DDR2 SDRAM runs its external data bus at twice the speed of DDR SDRAM and features a four-bit prefetch buffer, enabling faster performance. However, DDR2 SDRAM memory has greater latency than DDR SDRAM memory. Latency is a measure of how long it takes to receive information from memory; the higher the number, the greater the latency. Typical latency values for mainstream DDR2 memory are CL=5 and CL=6, compared to CL=2.5 and CL=3 for DDR memory. 240-pin memory modules use DDR2 SDRAM.

RAM Configurations—Discover how multi-channel memory layouts available on many systems can boost performance and how to install the modules. The small volume of the SODIMM form factor makes them ideal for use in computers with unusually constrained space. As you might have gathered from the intro, SODIMMs are primarily used in laptops. Not all laptops use SODIMM memory, though. As much as it is convenient for users that want the option to upgrade RAM in the future. It’s slightly more complex and expensive to implement than simply soldering the RAM chips directly onto the motherboard. Similar to what you would see on a mobile phone. a b c d e f g https://www.google.com/books/edition/Upgrading_and_Repairing_Laptops/xCXVGneKwScC?hl=en&gbpv=0 Memory Upgrade Considerations—This section lists the many different factors you need to take into account when selecting RAM for a particular system. DDR SODIMM: The original DDR (Double Data Rate) SODIMM, providing improved data rate over earlier SDRAM SODIMMs.Form factors [ edit ] A comparison between 200-pin DDR and DDR2 SDRAM SO-DIMMs, and a 204-pin DDR3 SO-DIMM module [13] Virtually all memory modules use some type of dynamic RAM ( DRAM) chips. DRAM requires frequent recharges of memory to retain its contents. SRAM SODIMMs are slightly smaller modules than DIMMs. These are almost half the size of DIMM modules, which are 67.6 mm (2.66 inches) in size. The width of the modules is the same. SODIMMs are designed to be used in notebooks and laptops and have fewer pins while maintaining the same functionality as DIMMs.

Razak Mohammed Ali. "DDR2 SDRAM interfaces for next-gen systems" (PDF). Electronic Engineering Times. Archived from the original (PDF) on 2007-09-26. Designed for use with Intel Skylake (6th generation Core i-series CPU); memory controller on motherboard/ processor must support both DDR3 and DDR4 memory JEDEC decided that the terms "dual-sided", "double-sided", or "dual-banked" were not correct when applied to registered DIMMs (RDIMMs).Most people don’t open up their laptops, though you should probably clean the fans occasionally. With how thin RAM is, you’d be forgiven for thinking that you could just fit a standard RAM DIMM in a laptop without needing any changes. That’s not the case, though. Internal volume is at a high premium in laptops. So they use a smaller form factor, SODIMM. Physical Appearance 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. Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn. 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. In this article, we are going to talk about the different form factors of RAM modules and how they are distinct from one another. RAM Form Factors DIMM