3.3 Installing a Motherboard
Installing a motherboard for the first time intimidates most people,
but it's really pretty easy if you do it by the
numbers. Before you get started, prepare a well-lighted working area,
ideally one with all-around access. The kitchen table (appropriately
protected) or a similar surface usually works well. Have all tools
and parts organized and ready to go. Open the box of each new
component, verify contents against the manual or packing list to make
sure no parts are missing, examine the components to ensure they
appear undamaged, and do at least a quick read-through of the manual
to familiarize yourself with the products.
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See also Chapter 28 for photographs of this process.
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3.3.1 Removing the Old Motherboard
If
you are replacing a motherboard, you must remove the old motherboard
before installing the new one. The exact steps vary according to the
motherboard and case, but use the following general steps:
Power down the PC and all attached devices. Disconnect all external
cables other than the power cord, noting which cable connects to
which port. Then move the PC to your work area and remove the cover
from the case. We can attest that one wayward case screw can destroy
a vacuum cleaner, so put the screws safely aside. An old egg carton
or ice cube tray makes a good parts organizer. If the PC power cord is connected to an outlet strip, surge
suppressor, or UPS, turn off the main power switch on that device,
and turn off the main PC power switch as well. This removes power
from the PC, but leaves the PC grounded.  |
With nearly all
AT form factor power supplies and motherboards, turning off the PC
power switch actually removes all power from the motherboard. With
ATX (and variant) power supplies and motherboards, turning off the
main PC power switch leaves some power flowing to the motherboard,
which supports such features as Wake-on-Ring
(WOR), Wake-on-LAN
(WOL), and Suspend to RAM
(STR).
Although the voltage present
is much too small to cause personal injury, working on a powered ATX
motherboard may damage the motherboard, CPU, memory, or other
components. Best practice when working on ATX motherboards is to use
an outlet strip or other device to remove power from the PC entirely.
If you must work on an ATX motherboard and have no such device,
disconnect the power cord from the wall receptacle before beginning
work. To avoid damaging components, touch the power supply to ground
yourself before handling the motherboard, CPU, memory, or other
static-sensitive components.
Even if you follow these procedures,
defective wiring or other components could cause a high-voltage
shock. For absolute safety, disconnect the PC power cord from the
wall receptacle. (Our lawyers made us say that.)
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Note the position and orientation of
each internal cable connected to an expansion card. If necessary,
sketch or photograph the connections to make sure you can reconnect
the cables as they were, and then remove those cables on the
expansion card. Remove the expansion cards and set them aside,
preferably on an antistatic surface, although a plain tabletop also
works well. Alternatively, you may be able to leave the cables
connected to the expansion cards and simply place the cards out of
the way, perhaps balanced on top of the power supply. Label and disconnect each cable that
connects to the system board, including those to the power supply, to
the front panel switches and LEDs, to back panel I/O ports, and to
fans. When you complete this step, the motherboard should not have
any obvious connections other than the mounting screws. In most cases, the motherboard mounts
directly to a fixed part of the chassis. In some cases, the
motherboard mounts to a removable tray. If your motherboard uses a
tray, remove the screws that secure the tray to the chassis and then
lift the tray out carefully, watching for overlooked cable
connections. Depending on the motherboard form factor, there may be
from three to a dozen or more screws securing the motherboard to the
chassis or tray. One or more screw holes may be occupied by nylon
spacers that snap in from the bottom of the motherboard and slide
into slots in the chassis. If the motherboard is secured only by
screws, remove all of them and then attempt to remove the motherboard
by lifting gently straight up. If one or more nylon spacers are
present (visible as small white nubs sticking up through screw
holes), rather than lift the mother board straight up, slide it
gently a fraction of an inch toward the left side of the chassis and
then lift straight up. Place the
old motherboard flat on a antistatic surface. Lacking that, put it on
the tabletop. If you are salvaging the CPU or memory, ground yourself
and remove those components. In any case, store the old motherboard
in the antstatic bag that the new motherboard arrived in, once that
bag is available.
3.3.2 Installing the New Motherboard
To
install the motherboard, take the following steps, observing
antistatic precautions throughout the process:
Touch the PC power supply to ground yourself, and then open the
antistatic bag that contains the new motherboard. Remove the new
motherboard from its antistatic bag, place the bag on a flat surface,
and place the motherboard on top of the antistatic bag. If you haven't done so already, read the motherboard
manual to determine how to configure it. Verify each diagram in the
manual against the actual motherboard to ensure that you can identify
the important switches, jumpers, and connectors. Configure the motherboard according to the instructions in the
manual. Recent motherboards may use only one or a few configuration
jumpers. Older technology motherboards may use jumpers to set
numerous options, including CPU speed, host bus speed, CPU voltage,
etc. Make sure to set all of these jumpers correctly, especially
those that control voltage, before you apply power to the board. After you have set all configuration jumpers properly, install the
CPU and memory according to the instructions supplied with the
motherboard and/or the components. Determine how the motherboard mounts to the chassis. Old motherboards
often used several snap-in nylon stand-off spacers and only a few
screws to secure the motherboard. Modern motherboards use all or
mostly screws, which secure to brass stand-off spacers. The important
issue is whether a given hole location in the motherboard is designed
to be grounded. If it is, it will mount with a screw to a conductive
brass stand-off spacer. If it isn't, it will mount
using a nonconductive nylon stand-off spacer. Using a conductive
brass connector where an insulating nylon connector was intended can
short out and destroy the motherboard. Using a nylon connector where
a brass connector was intended can cause the motherboard to operate
improperly or not at all, or to radiate excessive RFI. New
motherboards come with a plastic bag that contains screws and
stand-off spacers of the proper type. If yours does not and you are
not sure which type is required, refer to the motherboard
documentation or contact technical support. If the connectors
supplied with the motherboard do not include any insulating
stand-offs, it's generally a safe assumption that
all mounting holes are designed to be grounded to a brass stand-off
connector. Hold the motherboard over the chassis in the position that you will
mount it. Typically all or all but one of the holes in the
motherboard align with a stand-off spacer installed in the chassis.
The motherboard is secured to the chassis by passing a screw through
each of the motherboard screw holes and into the matching stand-off
spacer. The final hole, usually the one nearest the back left corner
of the motherboard, may use a slide-in spacer rather than a screw,
which makes it easier to line up the motherboard with the other
stand-off spacers. Most cases have many more mounting holes than are
needed to secure any particular motherboard. Visually align the holes
actually present in the motherboard with the chassis to determine
which subset of the chassis mounting holes will actually be used. If
you are building a new system, thread brass stand-off spacers into
the appropriate chassis mounting holes. If you are replacing a
motherboard, spacers may already be mounted in most or all of the
necessary locations. Add or relocate spacers as necessary to ensure
that each hole in the motherboard has a matching spacer.
Don't leave any motherboard mounting holes unused.
It's not that the motherboard is likely to go
anywhere if you don't use all the screws. Each of
those mounting holes provides support for the motherboard at a key
location. If you leave one or more of the mounting holes unsupported,
the motherboard may crack later when you are pressing hard to seat an
expansion card, CPU, or memory module. |
When installing a Slot 1 motherboard
that uses an old-style retention mechanism that must be installed
before the motherboard is mounted in the case, now is the time to
install it. Most new-style retention mechanisms can be installed
either before or after the motherboard is mounted, and many Slot 1
motherboards come with a folding retention mechanism already
installed, which requires only raising the arms to vertical and
locking them in place. |
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After
you've installed all necessary stand-off spacers,
slide the motherboard into position, aligning all holes with their
matching spacers. Secure the motherboard using the screws provided
with it, or the screws that secured the original motherboard. Reconnect the cables, including power
supply cables, ATA cables, floppy drive cable, the cables that link
the motherboard to front panel switches and LEDs, and the cables that
link the motherboard I/O ports to the back panel connectors. |
The motherboard package should include cables for the hard drive and
floppy drive. Always use these new cables rather than the old cables.
Not only are the new cables likely to be more reliable, but also they
are certain to be electrically and physically compatible with the
interface connectors on the new motherboard.
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Reinstall only the expansion cards needed to test the system
(usually just the video card), reconnect any cables that connect to
them, and then reconnect the external cables that link the system
unit to the monitor, keyboard, mouse, and so on. Verify that everything that needs to be
connected is connected, that everything is connected to the right
thing, and that you haven't left any tools where
they might short something out. Time for the smoke test. Turn on the monitor and then turn on
power to the system unit. The BIOS boot screen should appear on your
monitor. If no video appears, or if you hear a beep sequence other
than the normal single startup beep, you have something
misconfigured. Turn off the power immediately (or just pull the power
cord) and recheck all connections and settings
you've made. Once you're satisfied that the system is
working properly, shut it down, remove power from it, reinstall any
additional expansion cards, and restart the system. When the system begins a normal boot
sequence, press whatever key the BIOS boot screen prompts you to
press to enter CMOS Setup. If you have jumpered the motherboard in
configuration mode, special CMOS Setup options (e.g., setting CPU
speed or voltages) may be available now that will no longer be
available once you re-jumper the motherboard for normal operation.
Configure and save the CMOS Setup options, and then turn off power to
the system. If necessary,
re-jumper the motherboard for normal operation and then restart the
system. Verify proper system operation, particularly that the system
recognizes the hard drive(s) you have installed. Once you are sure
that the system is working as expected, shut it down, reinstall the
case cover, restart the system, and begin installing your operating
system and applications.
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If you replace the motherboard on a
Windows system, don't try to use your current
Windows installation unless you replaced a failed motherboard with an
identical model. At best, if the new motherboard is similar to the
old model, your existing Windows installation will almost work. If
the new motherboard is significantly different, Windows may not boot.
Even if it does boot, it will be unreliable. The best practice is to
format the hard drive, install a fresh copy of Windows, load the
chipset drivers for the new motherboard, install drivers for video,
audio, and other hardware devices, reinstall all of your
applications, and then restore your data. If you run Linux, you can
avoid all this. Linux generally takes motherboard upgrades in stride.
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3.3.3 Configuring CMOS
Each time a
system boots, the BIOS boot screen appears momentarily. While this
screen is being displayed, pressing a designated key runs the CMOS
Setup program, which resides in firmware. CMOS Setup is used to
configure CMOS and chipset settings ranging from those as obvious as
the Date and Time to those as obscure as memory timings and bus
settings.
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Recent Intel motherboards replace the standard BIOS boot screen with
an Intel-logo splash screen. Display the standard BIOS boot screen on
such systems by pressing the Esc key while the logo is visible.
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To invoke CMOS Setup, you normally press F1 (AMI), the Delete
key (Award), or F2 (Phoenix). Other BIOS manufacturers use different
keys, and some system and motherboard manufacturers modify a standard
BIOS to use another key. The key that invokes CMOS Setup nearly
always appears on the BIOS boot screen, but if your BIOS boot screen
doesn't show that key, try the Delete key, F1, F2,
F10, Ctrl-Alt-S, or refer to the documentation.
The
exact appearance of CMOS Setup and the available options depend on
the chipset, the BIOS make and version, and changes made to the BIOS
and CMOS Setup programs by manufacturers. For example, two
motherboards may use the same chipset, processor, and BIOS, but one
may give users complete freedom to configure chipset options, while
the other allows users access to only some of the settings and uses
hard-wired values for other settings.
All BIOSs default
to a reasonable set of CMOS settings, one that allows the system to
boot and function normally. Beyond that, it's up to
you to choose settings to configure the system as you want it and to
optimize its performance.
Some CMOS Setup options, the
so-called basic settings, are pretty obvious—things such as
time and date, hard drive parameters, power management, boot
sequence, and so on. Others, particularly those segregated as
advanced settings and chipset settings, are anything but obvious. The
brief help descriptions provided with them are usually not much help
unless you already understand the issue. The primary rule here is
if you don't understand what an option is
for, don't change it.
That's easy to say, but it ignores the fact
that accepting default settings for obscure options can result in a
PC that performs significantly below its potential. PC and
motherboard manufacturers differ in how
"aggressive" they are in choosing
default settings, particularly those for such things as memory timing
and wait states. Those that tend toward slower, more conservative
default settings say, with some justification, that they cannot
predict what components (particularly what speed and quality of
memory) a user will install. Choosing conservative settings allows
them to be sure that the motherboard will at least work, if not
optimally. Those who are more aggressive (often, PC vendors, who have
control of which memory and other components will be installed)
assume that users want the highest possible performance level and use
components that support those aggressive settings.
The
first place to look for detailed CMOS Setup instructions is in the
manual that came with the computer or motherboard. Some manufacturers
provide detailed explanations of general CMOS Setup and Chipset Setup
options, but many cover only basic CMOS Setup options and ignore
Chipset Setup completely. If that's the case with
your manual, you may be able to download detailed instructions from
the BIOS manufacturer's web site.
For a comprehensive
treatment of configuring and optimizing BIOS settings, order
The BIOS Companion, by Phil Croucher.
It's available in printed form, or as a PDF file at
one third the price (http://www.electrocution.com/computing/book_bios.asp).
Another useful reference is Wim's BIOS page
(http://www.wimsbios.com/).
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