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What's the Difference Between DDR1 DDR2 and DDR3?
By Brian Hopkin
What is the confusion about RAM? Most computer users do some research before
upgrading their system so they exactly know about a perfectly matching CPU,
motherboard and video card combination that will meet all their needs. But most
of them fail when it comes to RAM.
They just know the size of the RAM i.e. 1GB, 2GB or 4GB, but they don't know what
this DDR1, DDR2 or DDR3 is all about. So that's why I came up with a this guide
for buying a RAM, because it turns out that selecting the proper DDR variant is
a very important factor that determines how your overall system will perform, thus
every computer user should be well-advised to learn it.
DDR1 Specifications
DDR-DIM (Double Data Rate DIMM or DDR DIMM), or most popularly just plain DDR.
Double Data Rate interfaces provide two data transfers per differential clock.
The data becomes registered when the CK goes high (the + side), and /CK goes low
(the - side). DDR1 utilizes the JEDEC standard for Double Date Rate (DDR I) SDRAM.
Like all DDR RAM it is available as registered or un-buffered. Registered DIMMs
are generally known as FB-DIMMs and have their address and control lines buffered
in order to reduce signal loading. FB-DIMMs are considerably more expensive than
un-buffered DIMMs and are generally reserved for server use. There are very few
enthusiast/prosumer/gamers utilizing FB-DIMMs in their CPU's.
Un-buffered DIMMs don't feature address lines and control line buffering, so they
cost quite a bit less. However, they may be system-loading limited and are thus
generally restricted in the number that can be fitted onto one system. You'll find
that most un-buffered DIMMs these days can only be installed on one motherboard
to a maximum of 4 x 1GB.
Buffered or registered DIMMs don't have these limitations and server boards can
accommodate 8 x 1GB, 16 x 1GB or more. An interesting and largely unknown aspect
of un-buffered DDR DIMMs is that they are able to operate one clock cycle faster
then FB-DIMMs.
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