Hardware Reference
In-Depth Information
DDR3 DIMM Details
The 240-pin DDR3 DIMMs use two notches on each side to enable compatibility with
both low- and high-profile latched sockets. The connector key is offset with respect to the
center of the DIMM to prevent inserting it backward in the socket. The key notch is posi-
tionedinthecenteroftheareabetweenpins48and49onthefront(168/169ontheback),
and there is no voltage keying because all DDR3 DIMMs run on 1.5V.
Determining a Memory Module's Size and Features
Most memory modules are labeled with a sticker indicating the module's type, speed rat-
ing, and manufacturer. If you are attempting to determine whether existing memory can
be used in a new computer, or if you need to replace memory in an existing computer,
this information can be essential.
Figure 6.13
compares the markings on a typical 512MB
DDR2 module from Crucial Technology and a 2GB DDR2 module from Kingston Tech-
nology.
Figure 6.13
Markings on a 512MB DDR2 module (top) from Crucial Technology compared to markings
on a 2GB (bottom) DDR2 memory module from Kingston Technology.
However, if you have memory modules that are not labeled, you can still determine the
module type, speed, and capacity if the memory chips on the module are clearly labeled.
For example, assume you have a memory module with chips labeled as follows:
MT46V64M8TG-75
By using an Internet search engine such as Google and entering the number from one of
the memory chips, you can usually find the data sheet for the memory chips. Consider
the following example: Say you have a registered memory module and want to look up
the part number for the memory chips (usually eight or more chips) rather than the buffer
