While DDR SDRAM is sometimes rated inMHz, it is more often rated by throughput (MBps). Common speeds for DDR SDRAM include PC1600 (200MHz/1600Mbps), PC2100 (266MHz/2100Mbps), PC2700 (333MHz/2700Mbps), and PC3200 (400MHz/3200Mbps), but other speeds are available from some vendors. DDR2 SDRAM To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

DDR2's bus frequency is boosted by electrical interface improvements, on-die termination, prefetch buffers and off-chip drivers. However, latency is greatly increased as a trade-off. The DDR2 prefetch buffer is fourbits deep, whereas it is twobits deep for DDR. While DDR SDRAM has typical read latencies of between two and three bus cycles, DDR2 may have read latencies between three and nine cycles, although the typical range is between four and six. Thus, DDR2 memory must be operated at twice the data rate to achieve the same latency. Before working with any memory modules, turn the computer off and unplug it from the AC outlet. Be sure to employ electrostatic discharge (ESD) protection in the form of an ESD strap and ESD mat. Use an antistatic bag to hold the memory modules while you are not working with them. Before actually handling any components, touch an unpainted portion of the case chassis in a further effort to ground yourself. Try not to touch any of the chips, connectors, or circuitry of the memory module; hold them from the sides. DDR4 SODIMM: The latest iteration, providing further improvements in data rate and power efficiency over DDR3 SODIMMs. Compact Size: SODIMMs are more compact than regular DIMMs, making them suitable for use in laptops and other small form factor machines.a b https://www.google.com/books/edition/Upgrading_and_Repairing_PCs/E1p2FDL7P5QC?hl=en&gbpv=1&dq=simm+32+bits+dimm+64+bits&pg=PA442&printsec=frontcover 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. The maximum capacity on commercially available DDR2 DIMMs is 8GB, but chipset support and availability for those DIMMs is sparse and more common 2GB per DIMM are used. [ citation needed] [3] History [ edit ] 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] https://media-www.micron.com/-/media/client/global/documents/products/data-sheet/modules/parity_rdimm/htf36c256_512_1gx72pz.pdf?rev=e8e3928f09794d61809f92abf36bfb24 [ bare URL PDF]

DIMMs are often referred to as "single-sided" or " double-sided" to describe whether the DRAM chips are located on one or both sides of the module's printed circuit board (PCB). However, these terms may cause confusion, as the physical layout of the chips does not necessarily relate to how they are logically organized or accessed. 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 Memory chip type used on the module (SDRAM, DDR SDRAM, and so on)—Today, a particular memory module type uses only one type of memory. However, older memory module types such as early 168-pin DIMMs were available with different types of memory chips. You need to specify the right memory chip type in such cases to avoid conflicts with onboard memory and provide stable performance. DDR2 SDRAM was first produced by Samsung in 2001. In 2003, the JEDEC standards organization presented Samsung with its Technical Recognition Award for the company's efforts in developing and standardizing DDR2. [1] Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.A DIMM's capacity and other operational parameters may be identified with serial presence detect (SPD), an additional chip which contains information about the module type and timing for the memory controller to be configured correctly. The SPD EEPROM connects to the System Management Bus and may also contain thermal sensors ( TS-on-DIMM). [12] Error correction [ edit ] Most DIMMs are built using "×4" ("by four") or "×8" ("by eight") memory chips with up to nine chips per side; "×4" and "×8" refer to the data width of the DRAM chips in bits. High capacity DIMMs such as 256GB DIMMs can have up to 19 chips per side. The table below summarises the three common form factors of memory modules used in tech gadgets today: Estimated delivery times are provided to us by the respective delivery companies. We pass this information onto you, the customer. pin, used for SDR SDRAM (less frequently for FPM/EDO DRAM in workstations/servers, may be 3.3 or 5 V)

Buffered (registered) memory modules can be built with or without ECC support. However, most buffered memory modules are used by servers and include ECC support. Figure 4-2 compares a standard (unbuffered) memory module with a buffered (registered) memory module that also supports ECC. SO-DIMM vs DIMM To keep each generation of SODIMM distinct and prevent hardware damage caused by the different voltage requirements between generations, each generation of SODIMM RAM uses a different cut-out “key.” The key position between DDR and DDR2 SODIMM memory was very similar. Making them hard to tell apart outside direct side-by-side comparisons. Other generations of SODIMM RAM have more distinct key locations. Most desktop computers use full-sized memory modules known asDIMMs. However, laptop computers and some small-footprint mini-ITX motherboards and systems use reduced-size memory modules known as small outline DIMMs (SO-DIMMs or SODIMMS). DDR5 was introduced in 2021, and is the most recent generation of memory technology, marking a revolutionary jump in architecture. It’s arguably the biggest jump in memory technology we’ve seen since SDRAM. If you have been in the tech industry for a while, you will know that there are different types and sizes of RAM/memory modules available. When referring to RAM sizes, we mean its physical size, and not its capacity (4 GB, 16 GB, etc.).

Memory is not compatible across all motherboards

DDR2 SDRAM SPECIFICATION" (PDF). JESD79-2E. JEDEC. April 2008: 78 . Retrieved 2009-03-14. {{ cite journal}}: Cite journal requires |journal= ( help) Full-height 240-pin DDR2 and DDR3 DIMMs are all specified at a height of around 1.18 inches (30mm) by standards set by JEDEC. These form factors include 240-pin DIMM, SO-DIMM, Mini-DIMM and Micro-DIMM. [14] MicroDIMMs have only been iterated to DDR2. These are even smaller than SODIMMs and primarily used in printers and other non-memory-invasive devices. Like the DIMM form factor, no generation of SODIMM form factored RAM is compatible. This is because the form factor is essentially the only difference between DIMM and SODIMM. There aren’t any performance impacts beyond increased thermal constraints and physical capacity limits inherent to the smaller form factor.

Razak Mohammed Ali. "DDR2 SDRAM interfaces for next-gen systems" (PDF). Electronic Engineering Times. Archived from the original (PDF) on 2007-09-26.Ever-increasing amounts of RAM are needed as operating systems and applications get more powerful and add more features. Because RAM is one of the most popular upgrades to add to any laptop or desktop system during its lifespan, you need to understand how RAM works, which types of RAM exist, and how to add it to provide the biggest performance boost to the systems you maintain. When you install memory on a motherboard inside a working system, use the following tips to help your upgrade go smoothly and the module to work properly: Look for the “Form Factor” to know your module’s size. View the memory module’s form factor in Task Manager Figure 4-2 A standard unbuffered module (top) compared to a buffered (registered) module with ECC (bottom). 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.