Dell Precision WorkStation 420 User manual

DellPrecision™WorkStation420SystemsServiceManual
Desktop Chassis —Removing and Replacing Parts
Mini Tower Chassis —Removing and Replacing Parts
NOTE: You can obtain the latest version of this document from the Support section of the Dell Web site at http://www.dell.com.
Notes, Notices, and Cautions
Throughout this guide, blocks of text may be accompanied by an icon and printed in bold type or in italic type. These blocks are notes, notices,
and cautions, and they are used as follows:
Information in this document is subject to change without notice.
©1999 Dell Computer Corporation. All rights reserved.
Reproduction in any manner whatsoever without the written permission of Dell Computer Corporation is strictly forbidden.
Trademarks used in this text: Dell, Dell Precision, and the DELL logo are trademarks of Dell Computer Corporation.
Other trademarks and trade names may be used in this document to refer to either the entities claiming the marks and names or their products.
Dell Computer Corporation disclaims any proprietary interest in trademarks and trade names other than its own.
Initial release: 30 Nov 1999
NOTE: A NOTE indicates important information that helps you make better use of your system.
NOTICE: A NOTICE indicates either potential damage to hardware or loss of data and tells you how to avoid the problem.
CAUTION: A CAUTION indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate
injury.

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Desktop Chassis —RemovingandReplacingParts:DellPrecision™WorkStation420
Systems Service Manual
Overview
This section provides procedures for removing and replacing the components, assemblies, and subassemblies in the Dell Precision WorkStation
420 desktop chassis system.
Unless otherwise noted, each procedure assumes that the following conditions exist:
lYou have performed the steps in "Precautionary Measures."
lYou have removed the computer cover.
lYou can replace or reinstall a part by performing the removal procedure in reverse order unless additional information is provided.
Recommended Tools
Most of the procedures in this file require the use of one or more of the following tools:
l#2 Phillips-head screwdriver
lA wrist grounding strap as explained in "Precautionary Measures."
Precautionary Measures
Before you perform any procedure in this section, take a few moments to read the following caution for your personal safety and to prevent
damage to the system from electrostatic discharge (ESD).
Overview
Control Panel
Recommended Tools
Chassis Intrusion Switch
Precautionary Measures
Drives
Restarting the System
Power Supply
Computer Cover
System Board Components
Interior Service Label
RIMMs
Internal View
Microprocessor/Heat Sink Assembly
Front-Panel Inserts
Cooling Fan
Expansion Cards
Battery
Expansion-Card Guide
System Board
CAUTION: FOR YOUR PERSONAL SAFETY AND PROTECTION OF THE EQUIPMENT
Before you start to work on the system, perform the following steps in the sequence listed:
1. Turn off the computer and all peripherals.
2. Disconnect the computer and peripherals from their AC power sources. Also, disconnect any telephone or telecommunication lines
from the computer. Doing so reduces the potential for personal injury or shock.
3. If you are disconnecting a peripheral from the computer or are removing a component from the system board, wait 10 to 20 seconds
after disconnecting the computer from AC power before disconnecting the peripheral or removing the component to avoid possible
damage to the system board.
4. Wear a wrist grounding strap, and clip it to an unpainted metal surface, such as the padlock loop on the back of the chassis. If a wrist
grounding strap is not available, touch any unpainted metal surface on the back of the computer or on the computer chassis, such as

Restarting the System
To restart the system and reset the chassis intrusion detector, perform the following steps:
1. Replace the computer cover and reconnect the computer and peripherals to their power sources and turn them on.
ALERT! Cover was previously removed.
2. To reset the chassis intrusion detector, enter System Setup, select System Security,andresetChassis Intrusion to Enabled or
Enabled-Silent.
Computer Cover
Figure 1. Computer Cover Removal
To remove the desktop chassis computer cover, perform the following steps:
1. Turn off your computer and peripherals, and observe the Caution for Your Personal Safety and Protection of the Equipment described in
"Precautionary Measures."
2. If you have installed a padlock through the padlock ring on the back panel, remove the padlock.
3. Press in on the two securing buttons until the cover is free to swing up (see Figure 1).
4. Raise the back of the cover, and pivot it toward the front of the computer.
5. Lift the cover off the hooks at the front of the chassis.
Figure 2. Computer Cover Replacement
thepowersupply,todischargeanystaticchargefromyourbodybeforetouchinganythinginsidethecomputer.Whileyouwork,
periodically touch an unpainted metal surface on the computer chassis to dissipate any static electricity that might harm internal
components. Also avoid touching components or contacts on a card and avoid touching pins on a chip.
5. Verify that the standby power light-emitting diode (LED) on the system board is not on. If it is on, you may need to wait 10 to 30
seconds for it to go out (see Figure 22 or the internal service label).
NOTE: When you start the system, the chassis intrusion detector will cause the following message to be displayed at the next
system start-up:
NOTE: If a setup password has been assigned by someone else, contact the network administrator for information on resetting the
chassis intrusion detector.
1
Securing buttons (2)

To replace the computer cover, perform the following steps:
1. Check all cable connections, especially those that might have come loose during your work. Fold cables out of the way so that they do not
catch on the computer cover. Make sure cables are not routed over the drive bracket—they will prevent the cover from closing properly.
2. Check to see that no tools or extra parts (including screws) are left inside the computer's chassis.
3. Facing the left side of the computer, hold the cover at a slight angle as shown in Figure 2.
4. Fit the three cover hooks into the rectangular slots on the chassis. (It might be helpful to look down into the chassis to verify that the hooks are
in place.)
5. Pivot the cover down toward the back and into position. Make sure that the two securing buttons click into place.
Interior Service Label
Figure 3 shows the location of the interior service label on the inside of the top cover. This label shows the location of components within the
chassis and locations of system board components and connectors. It also contains an important notice that provides instructions you need to
follow to help prevent damage to your system board while you troubleshoot and service the computer system.
Figure 3. Interior Service Label
Internal View
Figure 4 shows the chassis with the top cover removed.
Figure 4. Chassis Orientation View
1
Securing buttons (2)

Front-Panel Inserts
Figure5.5.25-Inch Front-Panel Insert Removal
To remove a 5.25-inch front-panel insert, perform the following steps:
1. Hold the inverted top cover with the front facing you.
2. From the front of the top cover, use your thumbs to press inward on the insert until it snaps free of the cover.
To replace a 5.25-inch front-panel insert, position the two ring tabs over the posts on the inside of the bay opening, and then press the ring tabs
over the posts.
Expansion Cards
The Dell Precision 420 systems provide five 32-bit Peripheral Component Interconnect (PCI) expansion card slots. Slot 5 is shared with the RAID
port function.
The system contains five 32-bit expansion slots and a 32-bit AGP Pro 50 (4X) slot. If you use an AGP Pro 50 card, it occupies the AGP slot and
may occupy PCI slots 1 and 2. (See Figure6 for examples of these cards.)
Figure 6. Expansion Cards
1
Externally accessible drive bays
2
Hard-disk drive bracket
3
System board
4
Expansion card slots
5
Padlock ring
6
I/O panel connectors
7
Security cable slot
8
AC power receptacle
9
Power supply
10
Drive data cable
1
Front-panel insert
2
Ring tabs (2)
3
Posts (2)
NOTE: Before disconnecting a peripheral from the system or removing a component from the system board, verify that the standby
power LED on the system board has turned off. For the location of this LED, see Figure 22.

Figure 7. AGP Pro50 Card Extension
Figure 7 shows the card extension that may occupy PCI slots 1 and 2.
The following is a list of valid expansion-card combinations:
lOne AGP card and five PCI cards
lOne AGP card, four PCI cards, and one RAID card
lOne AGP Pro50 card and four PCI cards
lOne AGP Pro50 card, three PCI cards, and one RAID card
Expansion Card Removal
To remove an expansion card, perform the following steps.
1. Remove the computer cover.
2. Disconnect any cables connected to the card.
3. Unscrew the mounting bracket of the card you want to remove.
4. Grasp the card by its outside corners, and ease it out of its connector.
5. If you are removing the card permanently, install a metal filler bracket over the empty card-slot opening.
6. Replace the computer cover, and reconnect your computer and peripherals to their power sources and turn them on.
ALERT! Cover was previously removed.
7. To reset the chassis intrusion detector, enter System Setup, select System Security, and reset Chassis Intrusion to Enabled or
Enabled-Silent.
1
32-bit PCI expansion card
2
32-bit AGP card
CAUTION: Before you remove the computer cover, see "Precautionary Measures."
NOTE: Installing filler brackets over empty card-slot openings is necessary to maintain Federal Communications Commission
(FCC) certification of the system. The brackets also keep dust and dirt out of your computer.
NOTE: After you remove and replace the cover, the chassis intrusion detector will cause the following message to be displayed at
the next system start-up:

Expansion-Card Guide
Figure 8. Expansion-Card Guide Removal
To remove the expansion-card guide, perform the following steps:
1. Remove the hard-disk drive bracket.
2. Face the computer from the front.
From the outside of the chassis, press in with your fingers on the two tabs on the left side of the expansion-card guide (see Figure8). This
will release the left tabs of the card guide from the chassis.
3. Rotate the released side of the card guide away from the chassis.
The left side of the card guide will swing away from the chassis. With the left side of the card guide away from the chassis, you can then pull
the card guide back and out of the chassis, which releases the two right tabs.
Control Panel
Figure 9. Control Panel Removal
To remove the control panel, perform the following steps:
NOTE: If a setup password has been assigned by someone else, contact your network administrator for information on resetting
the chassis intrusion detector.
1
Left tabs (2)
2
Right tabs (2)
1
Thermal sensor cable
2
Control panel cable
3
Screw
4
Speaker cable
5
Chassis intrusion switch
cable
6
Control panel
7
Alignment hole
8
Guide pin
CAUTION: Before you remove the computer cover, see "Precautionary Measures"

1. Disconnect the control panel cable from the PANEL connector on the system board (see Figure 22 for the location of the PANEL connector).
2. Remove the mounting screw that secures the control panel to the chassis.
3. Disconnect the chassis intrusion switch cable connector from the control panel.
4. Disconnect the thermal sensor cable connector from the control panel.
5. Disconnect the speaker cable connector from the control panel.
6. Remove the control panel and cable from the chassis.
To reinstall the control panel, perform the removal procedure in reverse.
When you reinstall the control panel, be sure to align the control panel alignment hole and the guide pin located on the left side of the chassis front.
Chassis Intrusion Switch
Figure 10. Chassis Intrusion Switch Removal
To remove the chassis intrusion switch, perform the following steps:
1. From inside the chassis, slide the chassis intrusion switch to the side to release it from the chassis.
2. Disconnect the chassis intrusion switch cable connector from the control panel (see Figure9).
3. Remove the chassis intrusion switch and cable from the chassis.
Note the routing of the chassis intrusion cable to ensure the replacement is routed in the same manner.
4. Install the replacement chassis intrusion switch.
5. Replace the computer cover. Then reconnect your computer and peripherals to their power sources, and turn them on.
6. To reset the chassis intrusion detector, enter System Setup, select System Security,andresetChassis Intrusion to Enabled or
Enabled-Silent.
Drives
1
Control panel
2
Screw
3
Chassis intrusion switch
CAUTION: Before you remove the computer cover, see "Precautionary Measures"
NOTE: After you remove and replace the cover, the chassis intrusion detector will cause the following message to be
displayed at the next system start-up:
ALERT! Cover was previously removed.

Figure 11. Drive Locations
Diskette Drive Removal
To remove the 3.5-inch diskette drive assembly, perform the following steps:
1. Rotate the system power supply up and out of the system (see Figure 20).
2. Disconnect the DC power cable from the back of the diskette drive.
3. Disconnect the interface ribbon cable from the back of the diskette drive.
The other end of this ribbon cable is connected to the DISKETTE connector on the system board (see Figure 22 for the location of the
DISKETTE connector).
Note the routing of the DC power and interface ribbon cables through the chassis as you disconnect them. It is important to route the cables
properly when you replace them to prevent them from being pinched or crimped.
4. Press down on the retaining-tab release button (see Figure 12) and pull the drive assembly forward to remove it from the chassis.
Figure 12. Diskette Drive Removal
5. Remove the screw securing the diskette drive to the bracket (see Figure 13).
Figure 13. 3.5-Inch Drive Bracket
NOTE: In all of the following procedures, left and right refer to your left and right as you face the front of the computer.
1
Hard-disk drives
2
5.25-inchdrives
(CD-ROM drive
shown)
3
3.5-inch diskette
drive
CAUTION: Before you remove the computer cover, see "Precautionary Measures"
1
Retaining-tab release button

6. Rotate the left side of the diskette drive up until the drive is clear of the retaining tabs.
When you replace the 3.5-inch diskette drive on the bracket, be sure that the two retaining tabs on the right side of the bracket engage the
mounting holes in the side of the 3.5-inch diskette drive. Then replace the screw that holds the diskette drive to the bracket. To replace the 3.5-inch
diskette drive/bracket assembly in the chassis, slide the bracket tabs into the guides on the chassis until the bracket snaps into place. Reconnect
the DC power and interface cables.
5.25-Inch Diskette, LS-120 SuperDisk, Tape, or CD-ROM Drive Removal
To remove a diskette, LS-120 SuperDisk, tape, or CD-ROM drive, perform the following steps:
1. Remove the computer cover.
2. Disconnect the DC power cable and data cable from the back of the drive.
3. Squeeze the metal tabs that extend from each side of the drive bracket toward each other.
4. Pull the bracket out of the bay (see Figure 14).
Figure 14. 5.25-Inch Drive Removal
5. Turn the drive/bracket assembly upside down and remove the four screws that secure the drive to the bracket (see Figure 15).
Figure 15. 5.25-Inch Drive Bracket
1
3.5-inch diskette drive
2
Retaining tabs (2)
3
Bracket
4
Screw
1
Bracket tabs (2)
NOTE: For easier access inside the chassis, you may want to rotate the power supply out of the way temporarily. To do so, see Figure
20.

Hard-Disk Drive Bracket Removal
To remove the hard-disk drive bracket, perform the following steps.
NOTICE: If you are removing a hard-disk drive that contains data you want to keep, be sure you have a backup of your files before
you begin this procedure.
1. Remove the computer cover.
2. Disconnect the DC power cable and data cable from the drive.
3. Remove the screw holding the drive bracket to the drive bay.
4. Rotate the drive bracket upward to disengage it from the latch on the drive bay, slide it to the left, and lift it out of the chassis (seeFigure16).
Figure 16. Hard-Disk Drive Bracket Removal
Hard-Disk Drive Removal
To remove a hard-disk drive from the drive bracket, perform the following steps.
1
Metal tab
2
Drive bracket
3
Screws (4)
CAUTION: Before you remove the computer cover, see "Precautionary Measures."
1
Screw
2
Hooks (3)
3
Drive bracket
4
Latch on drive bay

1. Remove the four screws that secure the hard-disk drive to the drive bracket.
Retain these screws; they will be needed for the replacement drive.
2. Remove the hard-disk drive.
Hard-Disk Drive Replacement
To install a replacement hard-disk drive, perform the following steps.
1. If you are replacing a hard-disk drive that contains data you want to keep, be sure you have a backup of your files before you begin this
procedure.
2. Prepare the replacement drive for installation.
NOTICE: Wear a wrist grounding strap or ground yourself by touching an unpainted metal surface on the back of the
computer.
NOTICE: When you unpack the drive, do not set it on a hard surface, which may damage the drive. Instead, set the drive
on a surface such as a foam pad that will sufficiently cushion it.
Check the documentation for the drive to verify that it is configured for your computer system.
3. Remove the computer cover as instructed in "Computer Cover."
4. Remove the drive bracket from the chassis as instructed in "Hard-Disk Drive Bracket Removal."
5. Slide the drive into the chosen bay of the bracket, oriented so that the connectors on the back of the drive will face the back of the chassis
when the bracket is reinstalled (see Figure16).
6. Align the four screw holes of the drive and bracket. Insert and tighten the screws (see Figure17).
Figure 17. Installing a Hard-Disk Drive in the Bracket
7. Reinstall the hard-disk drive bracket in the chassis (see Figure18).
Install the bracket into the chassis by inserting the hooks in the slots on the front of the chassis. Then lower the bracket to the bottom of the
chassis, making sure that the latch on the drive bay is engaged. Replace the screw holding the drive bracket to the drive bay.
Figure 18. Installing the Drive Bracket in the Chassis
CAUTION: Before you remove the computer cover, see "Precautionary Measures."
CAUTION: Before you remove the computer cover, see "Precautionary Measures."
1
Screws (4)
2
Drive bracket
3
Drive

8. Connect a DC power cable to the power input connector on the back of the drive (see Figure19).
Check all connectors to be certain that they are properly cabled and firmly seated.
9. Connect one of the device connectors on the EIDE cable to the 40-pin interface connector on the back of the hard-disk drive.
NOTICE: You must match the colored strip on the EIDE cable with pin 1 on the drive's interface connector to avoid
possible damage to your system.
Figure 19. Attaching Hard-Disk Drive Cables
10. If it is not already connected, connect the other end of the EIDE cable to the IDE1 connector on the system board.
NOTICE: You must match the colored strip on the EIDE cable with pin 1 on the IDE1 connector to avoid possible damage to
your system.
11. Replace the computer cover. Then reconnect your computer and peripherals to their power sources, and turn them on.
12. If the drive you just installed is the primary drive, insert a bootable diskette into drive A.
13. Enter System Setup, and update Primary Drive 0 or Primary Drive 1.
After you update the System Setup settings, reboot the system.
14. Partition and logically format your drive before proceeding to the next step.
See the documentation for your operating system for instructions.
1
Screw
2
Hooks (3)
3
Drive bracket
4
Latch
NOTE: Ultra ATA/66 hard-disk drives require an 80-conductor cable to transfer data at full speed. The 80-conductor cable
has a 40-pin connector just like the Ultra ATA/33 cable but has twice as many wires within the cable itself. If you use an Ultra
ATA/33 cable with Ultra ATA/66 hard-disk drives, the drives will transfer data at Ultra ATA/33 speeds.
1
DC power cable
2
Power input connector on drive
3
Interface connector on drive
4
EIDE cable
5
IDE1 connector

15. Test the hard-disk drive by running the Dell Diagnostics (see the online System User's Guide for more information).
16. If the drive you just installed is the primary drive, install your operating system on the hard-disk drive.
Refer to the documentation that came with your operating system.
Power Supply
To access some components on the system board, you may have to rotate the system power supply out of the way. To rotate the power supply,
perform the following steps.
1. Remove the computer cover as instructed in "Computer Cover."
2. Disconnect the AC power cable from the AC power receptacle on the back of the power supply (see Figure 20).
Figure 20. Rotating the Power Supply
3. Free the power supply by pressing the securing tab labeled "RELEASE" and rotate it upward to a vertical position. See Figure20.
To remove the power supply, perform the following steps.
Figure 21. Removing the Power Supply
1. Remove the computer cover as instructed in "Computer Cover."
2. Disconnect the AC power cable from the AC power receptacle on the back of the power supply.
3. Disconnect the DC power cables that attach to the diskette drive, any installed 5.25-inch drives, and hard-disk drives mounted in the
internally-accessible drive bracket.
CAUTION: Before you remove the computer cover, see "Precautionary Measures."
1
Securing tab
2
Power supply
3
Release latch
CAUTION: Before you remove the computer cover, see "Precautionary Measures"
1
Power supply
2
Slot

4. Rotate the power supply up and out of the way of the system board (see Figure 20).
5. Disconnect the power supply connectors from the POWER_1 and POWER_2 connectors on the system board.
6. Carefully fold the DC power supply cables you have disconnected and place them outside the chassis.
7. With the power supply in its rotated position up and away from the system board and chassis, lift up on the front end of the power supply, and
then move that end of the power supply out, away from the chassis (see Figure 21).
System Board Components
Figure 22 shows the system board and the location of all its sockets and connectors.
Figure 22. System Board Components
1
CD-ROM drive audio connector
2
Main power 1 connector (desktop chassis)
3
Diskette connector
4
Main power 2 connector (desktop chassis)
5
Battery
6
RIMM (memory) sockets
7
SCSI narrow connector
8
Secondary EIDE connector
9
Suspend-To-RAM LED
10
Jumper block (see "System Board Jumpers")
11
System board screw
12
LVD SCSI connector
13
Primary EIDE connector
14
Standby power LED
15
Control panel connector
16
MT power 2 connector (mini tower chassis)
17
MT power 1 connector (mini tower chassis)
18
Modem (TAPI) connector
19
Card-cage fan power connector
20
Auxiliary sound input connector
21
PCI/RAID expansion card connector

System Board Jumpers
Figure 23 shows the location of the jumpers on the system board. Table1 lists the system board jumpers and their settings.
Figure 23. System Board Jumpers
Jumpers are small blocks on a circuit board with two or more pins emerging from them. Plastic plugs containing a wire fit down over the pins. The
wire connects the pins and creates a circuit.
NOTICE: Make sure your system is turned off before you change a jumper setting. Otherwise, damage to your system or
unpredictable results may occur.
To change a jumper setting, pull the plug off its pin(s) and carefully fit it down onto the pin(s) indicated.
Table 1. System Board Jumper Settings
22
Auxiliary hard-disk drive access LED connector
23
PCI expansion slots
24
AGP graphics slot
25
Remote wakeup on LAN connector
26
Primary processor 0 socket
27
Network cable connector
28
Diagnostic LEDs
29
USB connectors
30
Secondary processor 1 socket
31
Line-in connector
32
Line-out connector
33
Microphone Connector
34
Mouse/keyboard (stacked)
35
System fan power connector
36
Serial port 1/ serial port 2 (stacked)
37
Parallel port/external SCSI port (stacked)
Jumper
Setting
Description
PSWD
(default)
Password features are enabled.
Password features are disabled.
RTCRST
Real-time clock reset. Can be used for troubleshooting purposes.
jumpered unjumpered

System Board Labels
Table 2 lists the labels for connectors and sockets on your system board, and it gives a brief description of their functions.
Table 2. System Board Connector and Socket Labels
RIMMs
Connector or Socket Label
Description
AGP
AGP graphics card slot
AUX_LED
Hard-disk drive LED connector
Battery
Battery socket
CD_IN
CD-ROM audio interface connector
DISKETTE
Diskette/tape drive interface connector
ENET
Integrated NIC connector
EXT_SPKR
External speaker connector
FAN_CCAG
Card cage area fan power connector
FAN_SYS
Microprocessor fan power connector
HD_LED
Hard-disk drive
IDEn
EIDE interface connector
KEYB
Keyboard connector
LINE_OUT
External speaker connector
LINE_IN
Audio input connector
MIC
Microphone connector
MONITOR
Video connector
MOUSE
Mouse connector
MPWR1
Main power 1 connector (desktop)
MPWR2
Main power 2 connector (desktop)
MTPWR1
Main power 1 connector (mini tower)
MTPWR2
Main power 2 connector (mini tower)
PANEL
Control panel connector
PARALLEL
Parallel port connector; sometimes referred to as LPT1
PCIn
PCI expansion-card connector
POWER_1
Main power input connector
POWER_2
3.3-V power input connector
PROC_0
Primary microprocessor connector
PROC_1
Secondary microprocessor connector
RIMM_x
RIMM socket
SCSI
External SCSl port connector
SCSI_LVD
Internal LVD SCSl connector
SCSI_NARROW
Internal SCSl Narrow connector
SERIAL1/2
Serial port connectors
STANDBY_LED
Standby power LED
STR_LED
Suspend-to-RAM LED
USB
USB connectors
TAPI
Modem connector
WOL
Remote Wakeup on LAN power connector

To remove a Rambus in-line memory module (RIMM), perform the following steps.
1. Remove the computer cover.
2. PressthesecuringclipsoutwardsimultaneouslyuntiltheRIMMdisengagesandpopsoutslightlyfromthesocket(seeFigure24).
Figure 24. RIMM Removal
To install replacement memory, perform the following steps.
1. Remove the computer cover.
2. If necessary, remove any RIMMs that occupy sockets in which you plan to install the replacement RIMMs.
3. Install the RIMMs:
a. Locate the plastic securing clips at each end of the socket (see Figure 25).
b. Press the clips outward until they snap open.
c. Press the RIMM straight into the slot running down the center of the socket until the securing tabs snap into place around the ends
of the RIMM.
Figure 25. RIMM Installation
4. Replace the computer cover, and reconnect your computer and peripherals to their electrical outlets and turn them on.
CAUTION: Before you remove the computer cover, see "Precautionary Measures"
CAUTION: To avoid the possibility of electric shock, turn off the computer and any peripherals, disconnect them from their
electrical outlets, and then wait at least 5 seconds before you remove the computer cover.
CAUTION: The RIMMs can get extremely hot during system operation. To avoid dangerous burns, be sure that the RIMMs
have had sufficient time to cool before you touch them.
1
Securing clips (2)
CAUTION: To avoid the possibility of electric shock, turn off the computer and any peripherals, disconnect them from their
electrical outlets, and then wait at least 5 seconds before you remove the computer cover. Also, before you replace memory,
see the other precautions in "Precautionary Measures."
NOTES: If you are not installing a replacement RIMM at this time, you MUST remove the remaining RIMM in the pair and install a pair
of continuity modules (CRIMM).
When operating with a single pair of RIMMs, they MUST occupy sockets RIMMB-1 and RIMMA-2, with CRIMMs installed in RIMMB-3
and RIMMA-4.
1
Securing clips (2)
2
Notches (2)

The system detects that the new memory does not match the existing system configuration information and generates the following
message:
The amount of system memory has changed.
Strike the F1 key to continue, F2 to run the setup utility
5. Press <F2> to enter System Setup, and check the value for System Memory.
The system should have already changed the value of System Memory to reflect the newly installed memory. Verify the new total. If it is
correct, skip to step 7.
6. If the memory total is incorrect, turn off and disconnect your computer and peripherals from their electrical outlets. Remove the computer
cover, rotate the power supply, and check the installed RIMMs to make sure that they are seated properly in their sockets. Then repeat steps
3, 4, and 5.
7. Reset the chassis intrusion detector by entering System Setup, selecting System Security, and changing Chassis Intrusion to Enabled
or Enabled-Silent.
8. When the System Memory total is correct, press <Esc> to exit System Setup.
9. Run the Dell Diagnostics to verify that the RIMMs are operating properly.
Microprocessor/Heat Sink Assembly
To replace a microprocessor, perform the following steps.
1. Remove the computer cover according to the instructions in "Computer Cover."
2. Rotate the power supply as described in "Power Supply."
3. Remove the existing microprocessor from its connector.
a. Squeeze in on the two pairs of tabs on the airflow shroud and lift it away.
b. Unscrew and remove the two large thumbscrews that secure the heat sink to the system board.
c. Press outward on the guide bracket release latches.
d. Grasp the processor/heat sink assembly firmly, and pull it away from the guide bracket assembly assembly (see Figure 26).
You must use up to 15 pounds of force to disengage the processor from the connector.
Figure 26. Microprocessor Removal
NOTE: After you remove and replace the cover, the chassis intrusion detector causes the following message to appear on the
screen at the next system start-up:
ALERT! Cover was previously removed.
NOTE: If a setup password has been assigned by someone else, contact your network administrator for information on resetting
the chassis intrusion detector.
CAUTION: The microprocessors can get extremely hot during system operation. To avoid dangerous burns, be sure that the
microprocessors have had sufficient time to cool before you touch them.
CAUTION: To avoid the possibility of electric shock, turn off the computer and any peripherals, disconnect them from their
electrical outlets, and then wait at least 5 seconds before you remove the computer cover.
NOTE: Dell recommends that only a technically knowledgeable person perform this procedure.
CAUTION: Before you remove the computer cover, see "Precautionary Measures"
NOTE: Before disconnecting a peripheral from the system or removing a component from the system board, verify that the standby
power LED on the system board has turned off. For the location of this LED, see Figure 22.

Figure 27. Microprocessor Replacement
To insert the new microprocessor/heat sink assembly into the system board connector, perform the following steps (this procedure assumes the
microprocessor removal procedure was just performed).
1. Press the processor firmly into its connector until it is fully seated.
You must use up to 25 lb of force to fully seat the processor in its connector.
2. Install the two large thumbscrews that secure the heat sink to the system board.
3. Replace the airflow shroud.
1
Airflow shroud
2
Thumbscrews (2)
3
Processor/heat sink assembly
4
Guide bracket
5
Second processor
1
Airflow shroud
2
Thumbscrews (2)
3
Processor/heat sink assembly
4
Guide bracket
5
Second processor
NOTE: Dell recommends that only a technically knowledgeable person perform this procedure.
CAUTION: Before you remove the computer cover, see "Precautionary Measures"
NOTE: Before disconnecting a peripheral from the system or removing a component from the system board, verify that the standby
power LED on the system board has turned off. For the location of this LED, see Figure 22.