Dell Precision T5400 (Late 2007) - Manual (Page 189)

Adding and Replacing Parts 189
less than that installed. 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
• APIC(s)
• Integrated PCI devices, such as network connectors and SCSI controllers
• PCI cards
• Graphics card
• PCI Express cards (if applicable)
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 address
space, all installed computer memory is available for use only by the
operating system.
• If the total installed computer memory is equal to or greater than the
usable address space, a portion of installed memory is not available for use
by the operating system.
Removing Memory
CAUTION: Before you begin any of the procedures in this section, follow the
safety instructions in the Product Information Guide.
NOTICE: If you remove your original memory modules from the computer during a
memory upgrade, keep them separate from any new modules that you may have,
even if you purchased the new modules from Dell. If possible, do not pair an original
memory module with a new memory module. Otherwise, your computer may not
start properly.
NOTICE: To prevent static damage to components inside your computer, discharge
static electricity from your body before you touch any of your computer’s electronic
components. You can do so by touching an unpainted metal surface on the
computer chassis
NOTE: Memory purchased from Dell is covered under your computer warranty.