Hardware Reference
In-Depth Information
Irefertomemorymodulesmadebythechipmanufacturersas
first-party modules
,where-
as those made by module (but not chip) manufacturers I call
second-party modules
. Fin-
ally, those that are simply relabeled first- or second-party modules under a different name
are called
third-party modules
. I always prefer to purchase first- or second-party modules
if I can because they are better documented. In essence, they have a better pedigree, and
their quality is generally more assured. Not to mention that purchasing from the first or
second party eliminates one or more middlemen in the distribution process as well.
First-party manufacturers (where the same company makes the chips and the modules)
include Micron (
www.crucial.com
)
, Infineon (formerly Siemens), Samsung, Mitsubishi,
Toshiba, NEC, and others. Second-party companies that make the modules (but not the
chips) include Kingston, Viking, PNY, Simple Tech, Smart, Mushkin, and OCZ Techno-
logies. At the third-party level, you are not purchasing from a manufacturer but from a
reseller or remarketer instead.
Most of the large manufacturers don't sell small quantities of memory to individuals, but
some have set up factory outlet stores where individuals can purchase as little as a single
module. Oneofthelargestmemory manufacturers intheworld,Micron,sells direct tothe
consumer at
www.crucial.com
.
Because you are buying direct, the pricing at these outlets
is often competitive with second- and third-party suppliers.
Considerations in Purchasing DIMMs
When you are purchasing DIMMs, here are the main things to consider:
• Do you need SDR, DDR, DDR2, or DDR3 versions?
• Do you need ECC or non-ECC?
• Do you need standard (unbuffered) or registered versions?
• What speed grade do you need?
• Do you need a specific CAS latency?
Currently, DIMMs come in SDR (SDRAM), DDR, DDR2, and DDR3 versions. They are
not interchangeable because they use completely different signaling and have different
notches to prevent a mismatch. High-reliability systems such as servers can use ECC ver-
sions, although most desktop systems use the less-expensive non-ECC types. Most sys-
tems use standard unbuffered DIMMs, but file server or workstation motherboards de-
signed to support large amounts of memory might require registered DIMMs (which also
include ECC support). Registered DIMMs contain their own memory registers, enabling
the module to hold more memory than a standard DIMM. DIMMs come in a variety of
speeds, with the rule that you can always substitute a faster one for a slower one, but not
vice versa.
