1 - Types of RAM
RAM chips are packaged on small, printed circuit boards that fit into slots mounted on the motherboard. The type of
RAM that the motherboard supports decides the type of RAM you can buy for your PC. The type/amount of RAM the motherboard
supports can be found out from the specification set of the motherboard. In case you don’t have the specifications, the
same can be obtained from the vendor of the motherboard, by providing him with the name of the motherboard. In case you
are not aware of the name of the motherboard, you can find it out by reading the name printed on the motherboard.
Synchronous Dynamic RAM (SDRAM)
SDRAM has been around for more than a decade. SDRAM is designed to synchronize itself with the timing of the CPU, so that
the CPU no longer has to wait between memory accesses. It has several versions which differ primarily in bus speed: PC66,
PC100, and PC133. The numbers indicate each type's speed, as expressed in megahertz. While the high-speed memory may seem
the more appealing choice, your PC chipset ultimately makes that decision. The chipset has to support the type of RAM being
used. Owners of older PCs using 66MHz DIMMs can save some money by upgrading to higher-speed modules. However, it should be
remembered that in such cases the memory will work, but won’t run at full speed. Today SDRAM is primarily in the
low-cost PC and notebook markets.
Double Data Rate SDRAM (DDR SDRAM)
DDR RAM is the next-generation SDRAM technology, which rivals Rambus and allows the memory chip to perform transactions on
both the rising and falling edges of the clock cycle. It is an enhanced version of SDRAM that effectively runs at double
the bus speed of conventional SDRAM. |
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Extended Data Out ( EDO), Fast Page Mode (FPM)
If your PC is more than five years old, there is a high chance it might be using EDO or FPM memory. EDO RAM enables
the CPU to access memory faster than FPM. Although you can still find these legacy memory modules—usually priced
significantly higher than most new memory types—why bother? Chances are, such a system probably needs a lot more
upgrades than just memory.
Rambus Dynamic RAM (RDRAM)
RDRAM, developed by Rambus and championed by Intel, is the latest high-speed memory technology. Pentium 4 PCs equipped
with the Intel 850 chipset use RDRAM; newer Pentium 4 systems based on the Intel 845 chipset use less expensive SDRAM
or DDR SDRAM. RDRAM transfers data at speeds not possible with SDRAM. It offers a high-speed feature called "double
clocked," which allows operations to occur on both the rising and falling edges of the clock cycle. RDRAM has evolved
into a niche product used in high-end PCs, NT workstations, and game consoles.
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2 - Slots & Connectors
The number of memory slots on the motherboard determines the number of memory modules that can be fitted on the
motherboard. Most PCs have three to four slots. These slots are identified right on the motherboard. The motherboard’s
manual specifies the maximum memory the slot can accommodate. The amount and configuration of your PC's currently installed
memory will determine what you need to buy to reach the desired RAM.
Let’s take an example to understand this. Let’s assume that the PC can handle 128 MB of RAM. Two of its
three slots are filled with 32 MB modules. The cheapest option would be to buy another 64 MB module and reach the maximum
RAM possible. Another option would have been to discard the two 32 MB modules and replace it with a single 128 MB module.
This example explains the role of the memory slots on the motherboard in the choice of memory modules (RAM)
Connectors
A connector is the slot on the motherboard that the memory snaps into. Early motherboard manufacturers used proprietary
memory and users could not interchange memory. However, today most manufacturers offer a combination of SIMM, DIMM and RIMM
slots on their motherboards. SIMM, DIMM and RIMM refer not to memory types (SRAM, DRAM etc.), but to the modules (circuit
boards plus chips) in which RAM is packaged—Pin counts, names and bus widths.
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3 - Packaging
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SIMM
Single In-Line Memory Module allows the user to snap-in a group of nine modules onto the motherboard. Based on this
technology, the modules have to be installed in pairs and offer a 32-bit path for data transfer. These modules come
in 30 or 72 pins. SIMM’s are identified as white slots on the motherboard. |
DIMM
Dual In-Line Memory Module offers the user a 64-bit path for data transfer and was created for the Pentium line of
processors. Unlike SIMM’s they do not need to be installed in pairs. They can function independently. A single
module consists of 168 pins. DIMM’s are identified as black slots on the motherboard and are longer in length to
SIMM’s.
RIMM
Rambus In-Line Memory Module is specifically used for memory modules based on RDRAM technology from Rambus Inc. A single
module consists of 184 pins. Based on this technology a single memory module is capable of a data transfer speed of 1.6GB
per second. As these modules operate at such high speed they are enclosed in a heat dissipater. This technology will allow
devices to have an increased memory data transfer rate with just one or two modules as compared to the nine modules of the
SIMM.
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4 - Purchasing Factors
Warranty
Check out the warranty offered on the RAM. Some manufacturers offer life time warranties on the RAM.
Costs
The costs for these RAM vary, and it can be difficult to figure out the logic used in deciding the price of the RAM.
Sometimes slower memory may cost more than newer, faster RAM, simply because a more plentiful supply of the latter is
available. In general, as the module capacity rises, the price per megabyte of memory reduces.
Things to consider before buying RAM
You need to ask yourself the following questions before buying additional RAM
- How much memory do I need?
- How much memory will my system recognize?
- What kind of memory is compatible with my system?
Computers always seem to have less memory than required. New applications and 3D games require more and more memory to
function optimally. In such a scenario you need to add additional RAM to make sure your PC performs optimally. Now that you
are aware of the attributes to consider while purchasing RAM, you can get your self the additional RAM you always wanted
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