Hardware Reference
In-Depth Information
ThefastestofficialJEDEC-approvedstandardisDDR2-1066,whichiscomposedofchips
that run at an effective speed of 1,066MHz (really megatransfers per second), resulting in
modules designated PC2-8500 having a bandwidth of 8,533MBps. However, just as with
DDR, many of the module manufacturers produce even faster modules designed for over-
clocked systems. These are sold as modules with unofficial designations and performance
figures that exceed the standard ratings.
Table 6.8
shows the popular unofficial speed rat-
ings I've seen on the market. Note that because the speeds of these modules are beyond
the standard default motherboard andchipset speeds, youwon'tsee anadvantage tousing
these unless you are overclocking your system to match.
Table 6.8 Overclocked (Non-JEDEC) DDR2 Module (240-Pin DIMM) Speeds and Transfer Rates
Typically, you can find DDR2 modules rated between CL 3 and 6.
DDR3 SDRAM
DDR3 is the latest JEDEC memory standard. It enables higher levels of performance
along with lower power consumption and higher reliability than DDR2. JEDEC began
working on the DDR3 specification in June 2002, and the first DDR3 memory modules
and supporting chipsets (versions of the Intel 3x series) were released for Intel-based sys-
tems in mid-2007. Due to initial high cost and limited support, DDR3 didn't start to be-
come popular until late 2008 when Intel released the Core i7 processor, which included
an integrated tri-channel DDR3 memory controller. In early 2009, popularity increased
when AMD released Socket AM3 versions of the Phenom II, the first from AMD to sup-
