Make sure to notice how many DIMM slots motherboard choice provides. And to make sure you'll end up with at least one more slots of the appropriate type than you think you'll immediately need if you like to upgrade. You'll also need to make sure your motherboard supports the type of RAM you want to use—typically DDR and SDRAM if you use a motherboard asking for use of DIMM modules. And FPM or EDO DRAM if you'll be using SIMMs, but these are for far older motherboards.

Motherboards that boast a 800MHz system bus—also referred to as a front-side bus—should support DDR 2 DRAM memory speeds of 667MHz upto 800MHz. DDR2 DRAM DIMMs meant for upto 800MHz operation are usually rated at CL4, while older DDR 333MHz DIMMs are rated at CL2 and are often identified as PC3200 down to PC2100 DDR DRAM modules. If you run scientific or financial applications that must be excruciatingly correct all the time, you may want to insist on a motherboard that supports error correction code (ECC) memory with "REGISTERED" memory moduels. Using ECC memory lowers system performance and isn't necessary for the great majority of complicated and crucial system users.

You should also make a point of ensuring that your new motherboard will be able to accommodate a good bit more memory that you're likely ever to need, just in case. Most new motherboards can accept at least 2GB of MEMORY, and many accept 4GB or more.

Check your system operation manual that came with your computer. There should be a memory upgrade section which explains upgrading your systems memory.  Make attention to what is the correct memory module type before upgrading your system. Then confirm which type of MEMORY BANK (also know as slots or sockets) your system has, this way you can insure a perfect fit.

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Which kind of DRAM does your motherboard supports:

DDR-2, DDR, SDRAM, EDO, FPM

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What is DRAM ?

DRAM is short for Dynamic Random Access Memory, used as main memory in personal computers. The term dynamic indicates the memory must be constantly refreshed (reenergized) or it will loose its contents. RAM (Random Access Memory) is referred to the write or read of a cell or bit.

The term memory module refers to a printed circuit board on which several memory chips are mounted. The memory chips are usually DRAM chips, but recent system designs use cache chips mounted on memory modules as well.  Memory modules are installed on the PC’s motherboard.  They are used to make up the initial assembly and are installed into dedicated sockets. The number of DRAM chips mounted on the module and the capacity of the memory module is determined by the system. The design of the module, which determines a systems maximum memory capacity, is also based on the systems architecture.

The different types of DRAM

EDO (Extended Ddata Output) memory modules of this type of DRAM is 12 to 30 percent faster than Fast Page Mode and is a renovation in RAM chip technology. On only computer systems designed to support EDO this technology shortens the read cycle between the memory and CPU.

FPM (Fast Page Mode) memory modules was a 1995 simple scheme for improving memory performance that divided memory into pages ranging from 512 bytes to a few kilo-bytes long. Accessing DRAM is similar to finding information in a book. First, you turn to a particular page, then you select information from the page. Fast Page Mode enables the CPU (a computer main processor) to access new data in half the normal access time, as long as it is on the same page as the previous request.

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How do I remove and replace memory ?

Removing a DIMM:

Press the holding clips on both sides of the socket outward to release the DIMM. Gently pull the DIMM out of the socket.

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MEMORY BANK (Socket's)

Applying too much pressure can break the locking clips or damage the socket slot or Memory Module.

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Align pins 1 of the DIMM with pin 1 of the socket. Pin 1 is labeled 1 on both the DIMM and the socket.

Gently pushes the DIMM until the holding clips lock the DIMM into a vertical position.

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Key Definitions

Speed of Memory

In older memory module the speed is measured in nanoseconds, (1ns - 1/billionth of a second), the minimum access speed required for the RAM to work properly with a particular machine. Because this is an access time, the lower the number the faster the module. (i.e. - 7.5ns is faster than 10ns)

Buffered vs UnBuffered

Whether or not your computer uses buffered or non-buffered 168-pin DIMMs depends on its memory controller design. Some memory controller designs rely on the module to drive its own memory control signals. When the drivers (also referred to as buffers) are physically located on the module, you have a "buffered module." In non-buffered applications, the drivers/buffers are incorporated into the memory controller design, typically located on the motherboard. In this type of application, the memory control circuitry located on the motherboard is capable of driving the memory control signals for all devices plugged into the memory expansion bus. In this case, you would use a non-buffered module (i.e., a module that does not include its own buffers/drivers). If you are wondering which is better, buffered or non-buffered, it depends on your system requirements. It is strictly a matter of design. You can't use buffered modules in a memory application designed for non-buffered modules and you can't use non-buffered modules in an application designed for buffered modules. In fact, buffered and non-buffered 168-pin modules are keyed differently to prevent them from being plugged into non-compatible configurations.

SPD (Serial Presence Detect) code in EEPROM

SPD is programmed to optimize SDRAM DIMM timing performance when operating with older PC-100 systems. Located on a PC’s motherboard, the BIOS  reads information that is coded in SPD during system boot up, for accurate memory operation.

ESD (Electrostatic Discharge)

Memory modules are electrostatic sensitive. They can be damaged by electrostatic discharge (ESD).  Extreme care must be used in the handling and installing memory modules.  An ESD is significant because it can contain hundreds or even thousands of volts that can drastically damage the any electronic component. ESD may occur when you touch an object that is conducting electricity.

*SIMM (Single In-Line Memory Module)

A single In-Line Memory Module (SIMM) is a small printed circuit board (PCB) that consists of a number of DRAM chips and is designed to fit into a SIMM socket on a system board.  72-pin SIMMs are used in computer configurations that support 32-bit.

*30-pin vs 72 pin SIMMS

There are two types of SIMM's:  30-pin and 72-pin.  A 30-pin SIMM supports 8 data-bits, while a 72-pin SIMM supports 32 data-bits. Therefore, for a CPU such as the Intel Pentium, which processes 64-bits of data In one cycle, you will need eight 30-pin SIMMS to supply 64 bits. On the other hand, you will only need two 72-pins SIMMS to support 64-bits of data.  Of these two types, The 72-pin SIMM is more practical.

*DIMM (Dual in-Line Memory Module)

A Dual In Line Memory Module (DIMM) is a PCB that consists of a number of DRAM chips and is used to support a 64-bit or wider memory bus.  A 168-pin DIMM is usually found in desktop computers or servers.

*SO-DIMM (Small Outline Dual In-Line Memory Module)

A Small Outline Dual In-Line Memory Module is a PCB that consists of a number of DRAM chips and is used in supporting both 32-bit and 64-bit  memory bus'. A144 pin SO-DIMM is usually found in notebook / laptop systems.

*DDR2 (Rambus In-Line Memory Module)

DDR2 is the next-generation evolution of DDR memory technology. DDR2 memory features faster speeds, higher data bandwidths, lower power consumption, and enhanced thermal performance.

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DDR2 Naming Conventions and Bandwidths

PLEASE CLICK HERE TO VIEW THE INFORMATION CHART

DDR2 naming conventions are similar to DDR's. Unlike DDR, DDR2 can be mass-produced in speeds in excess of 400MHz, thereby delivering increased system performance.


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DDR2 Memory Chips

DDR memory chips are made with the familiar black resin Thin Small Outline Package (TSOP) as well as other chip types. DDR2 memory can no longer be manufactured into TSOP chips, and are only specified to be FBGA (Fine-pitch Ball Grid Array) chips, shown below:



DDR2 chips are also internally different from DDR memory chips. For example, DDR2 memory chips feature:
1.8 Volt operation, delivering about 50% less power usage as well as generating less heat compared to DDR
Memory signal termination inside the memory chip ("On-Die Termination") to improve signal quality and integrity (prevents reflected signal transmission errors at high speeds).
Operational enhancements to increase memory performance, efficiency, and timing margins
DDR2 CAS Latencies: 3, 4, and 5

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DDR2 vs DDR Modules

DDR2 memory modules have the same physical dimensions as their equivalent DDR counterparts, but have different pin configurations.

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