Understanding
and Troubleshooting
Your PC
Chapter Objectives
In this chapter, you will learn:
– About the different kinds of physical memory
(RAM) used on the motherboard
– About Windows memory management
– How to upgrade memory modules
– How to troubleshoot memory
Chapter 4: Managing Memory
2
RAM on the Motherboard
Memory is divided into two categories: ROM
and RAM
ROM retains its data when the computer is
turned off
RAM loses all of its data when the computer is
turned off
A computer system has two kinds of memory
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3
RAM on the Motherboard
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4
Static RAM Technologies
Memory caching is a method used to store
data or programs in SRAM for quick retrieval
Memory caching relies on SRAM chips to store
data and a cache controller to manage the
storage and retrieval of data from SRAM
When cache memory is located on the
motherboard, it either is located on individual
chips or on a memory module called cache on
a stick
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5
Static RAM Technologies
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6
Static RAM Technologies
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7
Dynamic RAM Technologies
 Dynamic RAM (DRAM)
needs to be refreshed every
few milliseconds
 DRAM is refreshed by the
memory controller
 In current PCs, DRAM is
always stored in DIMM,
RIMM, or SIMM modules,
which plug directly into a
bank on the mother board
 A bank is a location on the
motherboard that contains
slots for memory modules
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Dynamic RAM Technologies
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SIMM Technologies
SIMMs are rated by speed, measured in
nanoseconds
This speed is a measure of access time
Common SIMM speeds are 60, 70, or 80 ns
The smaller the speed rating is, the faster the
chip
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10
DIMM Technologies
A DIMM is a memory module that has pins on
opposite sides of the circuit board that do not
connect and thus form two sets of contacts
Contain 168 or 184 pins
Hold between 8 MB and 2 GB of RAM
Newer DIMMS hold chips that use
synchronous DRAM (SDRAM), which is DRAM
that runs in sync with the system clock and
thus runs faster than other types of DRAM
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RIMM Technologies
A RIMM is a memory module that houses
Rambus DRAM (RDRAM) chips, which are
much faster than SDRAM
With RIMMs, each socket must be filled to
maintain continuity throughout all sockets
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Factors Determining Memory Speeds
Speed of memory
Memory technology used
Latency rating
Type of error checking used
Single channel versus dual channel
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Factors Determining Memory Speeds
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Factors Determining Memory Speeds
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Windows Memory Management
The process of assigning memory address to
programs is called memory mapping
Once memory addresses have been assigned,
they can be used for communication with
software
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16
The Evolution of
OS Memory Management
Early CPUs only had 20 lines on the bus
available to handle addresses, which was 1MB
of memory, divided up as follows:
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The Evolution of
OS Memory Management
If the OS is low on RAM, it can store some
data on the hard drive, a method called virtual
memory
Data transferred to virtual memory is stored in
a file on the hard drive called a swap file or
paging file
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The Evolution of
OS Memory Management
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19
Memory Management in Windows NT,
Windows 2000, Windows XP,
and Windows Server 2003
 With this model, an application or device driver
indicates that it needs memory, but it does not have
to tell Windows which physical or which memory
addresses it wants
 Memory is allocated in 4K segments or pages
 Windows assigns a certain number of pages to an
application or device driver that needs memory
 Windows virtual memory manager handles managing
the memory addresses used for each page and can
choose to store these pages in RAM or in the hard
drive in the swap file named Pagefile.sys
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20
Memory Management in Windows NT,
Windows 2000, Windows XP,
and Windows Server 2003
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21
Upgrading Memory
Determine how much memory you have, and
how much you need
Determine the size and type of modules you
should buy to be compatible with the memory
you already have installed
Determine how much and what types of
memory you can fit on the motherboard
Determine how much you can afford
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22
Amount of Existing Memory and
Additional Memory Needed
Right-click My Computer on the Start menu,
click Properties, and then click the General tab
to determine how much memory you have
If possible upgrade a Windows XP system to
at least 512 MB of RAM
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23
Match Memory Modules
to the Motherboard
Newer motherboards support either ECC or
non-ECC memory
Check the motherboard documentation to
determine what to install
Computers use one or two methods to detect
memory
– Parallel Presence Detect (PPD)
– Serial Presence Detect (SPD)
Match the type of memory to the motherboard
requirements
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Memory Types Supported
by the Motherboard
Read the documentation for your motherboard
to determine what memory speed or speeds to
use on your board
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25
Memory Types Supported
by the Motherboard
Types of memory modules used on
motherboards:
– 72-pin SIMMs
– DIMMs
•
•
•
•
184-pin DDR SDRAM
2.5V
Unbuffered
DDR400
– RIMM Modules
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26
Memory Types Supported
by the Motherboard
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27
Purchasing Memory Modules
Before purchasing memory, check your
motherboard documentation to determine if
you need proprietary memory
Proprietary memory typically costs more than
memory purchased from a third-party company
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Reading Ads for Memory Modules
 Advertisements typically include information about
the speed, the size, the type of module, and more
 For DIMMS, the add might list the density of the
module, which is written as two numbers separated
by x
 Density allows you to determine three important
things about the memory module:
– Width of the data bus
– ECC or non-ECC
– Module size
 For Rambus memory, ads list the module size in MB
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Reading Ads for Memory Modules
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30
Determining the Quality
of Memory Modules
Poor-quality memory chips can cause frequent
application errors, errors that cause the system
to freeze, and General Protection Fault (GPF)
errors
Consider the following when shopping for
memory chips:
– Tin or Gold Leads
– Remanufactured and Used Modules
– Re-Marked Chips
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Installing Memory
Protect the chips against static electricity
Always use a ground bracelet as you work
Be sure you have written down CMOS
settings, and make a recovery disk if you do
not already have one
Turn off the computer and unplug it before you
remove the cover
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Installing Memory
Installing a SIMM module
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Installing Memory
Installing a DIMM module
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Installing Memory
After you placed each module securely in its
slot, turn on your PC and watch POST count
the amount of memory during the boot
process, if possible
Check the total memory on the system in the
System Properties window to make sure it
reads all memory you have installed
Update your records with the new memory
configuration in your computer
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Troubleshooting Memory
 Check that you have installed memory modules that
are supported by your motherboard
 Check that you have installed the right module size,
as stated in the motherboard documentation
 Remove and reinstall each module. Confirm that the
memory modules are properly seated, and that each
module sits in the socket at the same height as other
modules
 Remove the newly installed memory, place the
memory in different sockets or slots, and check
whether the error message disappears
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Troubleshooting Memory
 Try installing the new memory without the old
installed. If the new memory works without the old,
then the new and old modules are not compatible
 Clean the module edge connectors with a soft cloth
or contact cleaner. Blow or vacuum dust from the
memory sockets
 Try flashing your BIOS, using the steps outlined in
Chapter 3. It is possible the BIOS has problems with
the new memory that a BIOS upgrade can solve
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37
Troubleshooting Memory
 If you have recurring errors and have not just upgraded the
memory, try the following:
– Run a current version of antivirus software to check for viruses
– The problem might be with the OS or applications. Download the latest
patches for your operating system and application software from the
manufacturers’ Web sites
– If you have just installed new hardware, the hardware device might be
causing an error, which the OS interprets as a memory error. Try
uninstalling the new hardware
– A Windows error that occurs randomly and generates an error message
with exception fault 0E at >>0137:BFF9z5d0 or similar text is probably
a memory error. Test, reseat, or replace RAM
– Sometimes a problem can result from a bad socket or a broken trace (a
fine printed wire or circuit) on the motherboard. Check the motherboard
for visible problems. If you find an issue, you might have to replace the
entire motherboard
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38
Chapter Summary
In this chapter, you learned:
– About the different kinds of physical memory
(RAM) used on the motherboard
– About Windows memory management
– How to upgrade memory modules
– How to troubleshoot memory
Chapter 4: Managing Memory
39
Understanding
and Troubleshooting
Your PC
Chapter 4 Complete