Ddr2 Memory Overview; Addressing Memory With 4-Gb Configurations - Dell OptiPlex GX520 User Manual

Back to Contents Page
Memory
Dell™ OptiPlex™ GX520 User's Guide
DDR2 Memory Overview
Addressing Memory With 4-GB Configurations
Removing Memory
Replacing/Adding Additional Memory
For information on the type of memory supported by your computer, see the "Memory" section of the specifications for your computer:
Mini Tower Computer Specifications
l
Desktop Computer Specifications
l
Small Form Factor Computer Specifications
l
NOTICE: Before you install new memory modules, download the most recent BIOS for your computer from the Dell Support website at
support.dell.com.
DDR2 Memory Overview
Dual-channel DDR2 memory modules should be installed in pairs of matched memory size. If the DDR2 memory modules are not installed with the same amount
of memory in each channel, the computer will continue to operate, but with a slight reduction in performance. See the label in the upper-right corner of the
module to determine the module's capacity.
NOTE: Always install DDR2 memory modules in the order indicated on the system board.
The recommended memory configurations are:
A pair of matched memory modules installed in connectors DIMM1 and DIMM2
l
or
A memory module installed in connector DIMM1
l
NOTICE: Do not install ECC memory modules. Doing so may cause the system not to boot or affect performance.
Be sure to install a single memory module in DIMM1, the connector closer to the processor, before you install a module in the other connector.
Addressing Memory With 4-GB Configurations
This computer supports a maximum of 4 GB of memory when you use two 2-GB DIMMs. Current operating systems, such as Microsoft® Windows® XP, can only
use a maximum of 4 GB of address space; however, the amount of memory available to the operating system is less than 4 GB. Certain components within the
computer require address space in the 4-GB range. Any address space reserved for these components cannot be used by computer memory.
The following components require memory address space:
System ROM
l
APIC(s)
l
Integrated PCI devices, such as network connectors and SCSI controllers
l
PCI cards
l
Graphics card
l
PCI Express cards (if applicable)
l
At start-up, the BIOS identifies the components that require address space. The BIOS dynamically calculates the amount of reserved address space required.
The BIOS then subtracts the reserved address space from 4 GB to determine the amount of usable space.
If the total installed computer memory is less than the usable space, all installed computer memory is available for use only by the operating system.
l
If the total installed computer memory is equal to or greater than the usable address space, a small portion of installed memory is available for use by
l
the operating system.