Memory
Why do I need to upgrade
RAM?
- I want to upgrade
my OS to Windows XP
(RAM: 256MB recommended)
- I feel too slow if
I load too many programs
at the same time
- My harddisk's LED
keeps flashing - a symtom
that the PC is running
out of memory(RAM) and
started using the harddisk
intensively for caching
purpose by means of
virtual memory
Memory - RAM - Random
Access Memory. RAM is
by far the easiest and
most productive of upgrades
to do. RAM is your computer's
short-term memory, which
it uses to store the information
that you are working on.
Adding memory will allow
your applications to open
faster. There are a great
number of different types
of memory (EDO, PC66,
PC100, PC133, DDR2300,
DDR3300 etc.).
The SDRAM DIMM is the
most widely used memory
type in older standard
desktop systems. SDRAM
has various speeds; 66Mhz
(PC66), 100Mhz (PC100)
and 133 Mhz (PC133).
SDRAM was a huge improvement
on previous types of RAM
because it eliminated
a lot of wait time. Traditionally
the system bus (which
is all the circuitry on
the motherboard that moves
data around a computer)
and RAM had to wait for
each other to do their
part in processing information.
SDRAM changed that. Now
the bus and the RAM work
at the same time. There's
no tag team silliness
going on.
NOTE: DIMM stands
for dual inline memory
module, SDRAM stands for
Synchronous Dynamic RAM
SDRAM is a kind of memory
chip that was introduced
around the time that Pentium
II computers appeared.
If you have one of those
computers today, chances
are that you are in the
market to add memory to
extend the life of the
computer.
Only buy the correct
speed for your motherboard.
You need to check the
motherboard's specification
before making the purchase.
If the specs says that
the motherboard only supports
100 MHz SDRAM, then buy
only PC100 SDRAM only.
66MHz modules will not
work on a 100/133MHz bus
speed.
While some 133Mhz module
will work on 100Mhz motherboard,
do not assume all 133Mhz
memory work on 100Mhz
motherboard.
What if PC100 RAM
is not available in the
market? Can I mix the
PC133 with my existing
PC100 RAM?
If your motherboard is
able to support PC133
and you already have an
existing PC100, you can
mix the PC133 with PC100.
The PC will configure
itself to run at the speed
of the slowest RAM installed.
So if you can afford to
dump your PC100 RAM and
replace it with PC 133
you can take advantage
of the faster technology.
I won't advise you to
do so, as PC133 is only
slightly faster than PC100
RAM.
Single Sided (x4)
- Newer standard
In addition, please check
with motherboard manufacture
to see if the motherboard
bios support 256MB(32x4)
or 512MB(64x4) new standard.
If not, it will only read
half of the memory capacity
even though your computer
starts up normally.
Please contact your motherboard
manufacture to update
the bios to accept (32x4)
or (64x4) new standard.
Generally, for motherboard
that accept (32x4) or
(64x4), it must be able
to take 512 MB in each
memory slot, If the motherboard
doesn't support (32x4)
or (64x4) standard, please
order the (16x8) or (32x8)
standard.
Double Sided (x8)
- Older standard
If you are upgrading
an old mb (say P3), choose
PC133 256 mb double sided
SDRAM. It fits all older
motherboards that do not
support single sided SDRAM.
DDR SDRAM
You may also have heard
of DDR SDRAM. This is
an even faster kind of
memory called double data
rate memory. DDR memory
moves data at 266MHz,
but don't call it PC266
SDRAM.
To use DDR memory, your
system has to specifically
support the technology.
Typically PCs that run
Pentium III or Pentium
4 processors that run
at 1 GHz or faster will
support DDR RAM, but don't
assume that all will.
AMD Althon processor-based
machines also tend to
support DDR SDRAM. Check
with your computer maker
to ensure that the motherboard
supports DDR RAM. Or look
up your system on Crucial.com
to find out.
When buying DDR SDRAM
you'll be faced with few
choices. They are PC1600,
PC2100, PC2700, PC3200(DDR400)
...
While your motherboard
may support DDR memory,
you will need to check
to see that it supports
PC2100 DDR SDRAM. Some
early models of DDR-enabled
motherboards only work
with PC1600. You also
need to ensure that the
processor for your computer
can support PC2100.
PC1600 DDR is designed
for motherboards and processors
with a 200 MHz bus and
PC2100 DDR is designed
for a motherboards and
processors with a 266
MHz bus. Remember that
the bus is all those circuits
on the motherboard that
moves data around. They
are kind of like data
highways that run between
the processor and RAM
and all the other components
in a computer.
Once again, a computer
with a mix of PC2100 and
PC1600 DDR SDRAM will
default to the slower
RAM speed.
If you need more info,
check out Crucial.com's
amazing RAM guide. Go
to Crucial.com and click
the "Library"
tab for lots more useful
RAM information.
It's easy to figure out
what RAM your system needs.
You just select your brand
and make and model of
the system and then Crucial
shows you which RAM will
work with your computer.
Pin Configuration
DDR2 240-pin DIMM
DDR 184-pin DIMM
PC133 168-pin DIMM
PC100 168-pin DIMM
Terminology
Most desktop computer
use non-ECC (error correction),
non-registered, and non-buffered
memory modules.
ECC and registered
memory modules are normally
used by servers that require
these features and ECC
memory are far more expensive
than the non-ECC memory.
CL stands for
CAS Latency.
When a module is labeled
CL2 it means there are
only two clock cycles
before the module can
send the first block of
data.
CL3 means there
are three cycles before
the first block of data
is sent.
Cl2 is considered
to be a small percentage
faster than CL3 modules.
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