Memory
RAM is our working memory storage.
All the data, which the PC uses and works with during operation, are stored
here. Data are stored on drives, typically the hard drive. However, for the CPU
to work with those data, they must be read into the working memory storage,
which is made up of RAM chips.
Memory Overview
RAM (Random Access Memory) is the
basic working memory of your computer system. A computer used RAM to hold
volatile (Temporary) instructions and data needed for processing. Volatile
simply means that it is not permanent, which means anything written to RAM will
be loses if the machine loses power or if it's turned off.
Another key point about RAM is
that data stored init can be accessed much more quickly than data retrieved
from the hard disk. Theoretically data retrieved from RAM is accessed 100 to
300 times faster then the same information from a hard disk, optical drive, or
a floppy.
Memory is measured in bytes, so
you'll often encounter the terms megabyte (MB) and gigabyte (GB) in describing
RAM sizes (a megabyte is a million bytes; a gigabyte, a billion). RAM is
something that you do not want to skimp on. You can choose a slower processor,
but with RAM you want as much as you can get.
Memory Types
There are many types of memory
used today. They differ mainly in available speeds and cost. Motherboards are
limited to one type of memory. Common memory types include:
SDRAM
Almost all systems used to ship
with 3.3 volt, 168-pin SDRAM DIMMs. SDRAM is not an extension of older EDO DRAM
but a new type of DRAM altogether. SDRAM started out running at 66 MHz, while
older fast page mode DRAM and EDO max out at 50 MHz. SDRAM is able to scale to
133 MHz (PC133) officially, and unofficially up to 180MHz or higher. As
processors get faster, new generations of memory such as DDR and RDRAM are
required to get proper performance.
DDR Memory (184-pin DIMMS)
These were introduced in 2002 to
replace the earlier SDRAM format. To use this type of memory you need a 184-pin
socket for the module to fit into.
DDR Memory is available in
different speeds of PC2100, PC2700, PC3200 (DDR400), and PC4000 (DDR500). The
modules can be used singly or how desired however you cannot mix different
speeds together.
DDR2 Memory (240-pin DIMMS)
This format builds on the
technology of DDR . This standard has more pins and its main developments are
the ability to run faster whilst consuming less power.
To use DDR2 memory you need a
240-pin socket for the module to slot on your motherboard. DDR2 Memory is available
in many different speeds including PC2-3200 (DDR2400), PC2-4200 (DDR2533), and
PC2-5300 (DDR-667).
The modules can be used singly or
you can install different speeds of DDR2 memory together if your motherboard
supports the faster speed however faster modules will perform at the lower
speed.
This may be worth considering if
you want to run Dual-Channel memory where you must use the same speed and
ideally matching pairs to ensure compatibility.
DDR3 Memory (240-pins)
THIS is the latest memory standard
(2008 onwards) taking over from the previous DDR and DDR2 standards. Although
DDR3 comes with 240-pins the same as DDR2 the notch is in a different place so
people can not install the wrong type.
DDR3 is not backward compatible
with DDR2 in addition to the notch the voltage runs at a lower 1.5V than DDR2
1.8V. DDR3 memory will not fit into a standard DDR2 DIMM socket or an earlier
DDR memory socket.
To use DDR3 memory, your system
motherboard must have 240-pin DIMM slots and a DDR3-enabled chipset.
Memory Installation
Memory isn't hard to install.
First, make sure to take the usual static-avoidance measures, including wearing
an anti-static wrist strap. Touch a piece of bare metal on the case before
proceeding. With DIMMs, insert the module straight in the slot, taking care to
match up the indentation in the module with the notch in the slot see below
figure.
Then, make sure the plastic clips
are closed as shown in below figure.
General rules for memory
installation:
Use the correct memory for the
motherboard.
Follow all instructions from the
computer/motherboard and memory manufacturers.
Make sure all the memory modules
match.
Start at the lowest number memory
slot, either 0 or 1.
Insert the memory in capacity
order starting with the highest-capacity module in the lowest number slot.
After you have installed the
memory, boot the computer and check the memory.
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