Maintenance and Service Guide

Table Of Contents
The system automatically operates in single-channel mode, dual-channel mode, or ex mode, depending on
how the DIMMs are installed.
NOTE: Single-channel and unbalanced dual-channel memory congurations results in inferior graphics
performance.
The system operates in single-channel mode if the DIMM sockets are populated in one channel only.
The system will operate in a higher-performing dual-channel mode if the total memory capacity of the
DIMMs in ch
annel A is equal to the total memory capacity of the DIMMs in channel B. The technology and
device width can vary between the channels. For example, if channel A is populated with two 8 GB DIMMs
and channel B is populated with one 16 GB DIMM, the system will operate in dual-channel mode.
In any mode, the maximum operational speed is determined by the slowest DIMM in the system.
IMPORTANT: You must disconnect the power cord and wait approximately 30 seconds for the power to
dr
ain before adding or removing memory modules. Regardless of the power state, voltage is always supplied
to the memory modules as long as the computer is plugged into an active AC outlet. Adding or removing
memory modules while voltage is present can cause irreparable damage to the memory modules or system
board.
The memory module sockets have gold-plated metal contacts. When upgrading the memory, it is important
to use memory modules with gold-plated metal contacts to prevent corrosion, oxidation, or both resulting
from having incompatible metals in contact with each other.
Static electricity can damage the electronic components of the computer or optional cards. Before beginning
these procedures, be sure that you are discharged of static electricity by briey touching a grounded metal
object. For more information, see
Electrostatic discharge information on page 11.
When handling a memory module, be careful not to touch any of the contacts. Doing so can damage the
modul
e.
Before replacing the memory modules, follow these steps:
1. Prepare the computer for disassembly (Preparation for disassembly on page 21).
2. Remove the access panel (Access panel on page 21).
Replace a memory module:
1. To remove a memory module, open both latches of the memory module socket (1), and then remove the
memory module from the socket
(2).
Memory modules (DIMMs) 27