Hardware Reference
In-Depth Information
whose Athlon 64 and Opteron processor families included integrated DDR memory con-
trollers. AMD processor-based systems first supported DDR2 in mid-2006, with the re-
lease of socket AM2 motherboards and processors to match. (AMD's Socket F, otherwise
known as 1207 FX, also supports DDR2 memory.)
It is interesting to note that AMD was almost two years behind Intel in the transition from
DDRtoDDR2.ThisisbecauseAMDincludedthememorycontrollerinitsAthlon64and
all subsequent processors, rather than incorporating the memory controller in the chipset
North Bridge, as with the more traditional Intel designs. Although there are advantages to
integrating the memory controller in the CPU, one disadvantage is the inability to quickly
adopt new memory architectures because doing so requires that both the processor and
processor socket be redesigned. However, with the release of the Core i-Series processors
in 2008, Intel also moved the memory controller from the chipset into the processor, thus
putting Intel and AMD in the same situation in terms of memory architecture.
In addition to providing greater speeds and bandwidth, DDR2 has other advantages. It
uses lower voltage than conventional DDR (1.8V versus 2.5V), so power consumption
andheatgenerationarereduced.BecauseofthegreaternumberofpinsrequiredonDDR2
chips, the chips typically use fine-pitch ball grid array (FBGA) packaging rather than the
thin small outline package (TSOP) chip packaging used by most DDR and convention-
al SDRAM chips. FPGA chips connect to the substrate (meaning the memory module in
most cases) via tightly spaced solder balls on the base of the chip.
Table6.7
showsthevariousofficialJEDEC-approvedDDR2moduletypesandbandwidth
specifications.
Table 6.7 JEDEC Standard DDR2 Module (240-Pin DIMM) Speeds and Transfer Rates
