Apple Memory DIMMs User Manual
 Mac Pro  
Memory DIMMs  
Replacement Instructions  
Note: Follow these instructions carefully. Failure to do so could damage your equipment and  
First Steps  
void its warranty.  
1
2
Shut down computer.  
Wait 10 minutes.  
Warning: Parts inside  
computer can be very  
hot. Allow computer  
to cool down before  
continuing.  
3
Unplug all external  
cables except power  
cord.  
4
5
Touch metal PCI cover  
on back of computer.  
Unplug power cord.  
Opening the  
Computer  
1
Hold side access  
panel and lift latch on  
back of computer.  
Warning: Edges of  
access panel and  
enclosure can be  
sharp. Be careful  
when handling.  
2
Remove access panel  
and place it on flat  
surface covered by  
soft, clean cloth.  
© 2009 Apple Inc. All rights reserved.  
073-1246 Rev. B  
1
Filling Slots  
If you are installing DIMMs  
that are of the same size,  
follow the order in the  
tables on pages 3 and 4.  
If you are installing  
different-size DIMMs, also  
refer to“Memory Slot  
Utility”on page 4.  
Quad-Core Memory  
Quad-core computers  
have four memory slots.  
You can install 1 GB or  
2 GB DIMMs for a total of  
up to 8 GB of memory.  
The processor’s memory  
controller has three  
memory channels. DIMM  
slots 1 and 2 have their  
own channels; slots 3 and  
4 share a channel.  
For optimal memory  
bandwidth, all three  
memory channels should  
be used, and memory  
should be balanced across  
the three channels.  
If you have  
Two DIMMs  
Three DIMMs  
Four DIMMs  
Fill these slots  
1 and 2  
1, 2, and 3  
1, 2, 3, and 4  
Note: Populating slot 4  
slightly drops maximum  
memory bandwidth,  
but depending on the  
applications used, overall  
system performance may  
benefit from the larger  
amount of memory.  
© 2009 Apple Inc. All rights reserved.  
073-1246 Rev. B  
3
8-Core Memory  
Eight-core computers  
have eight memory slots,  
four per processor. You  
can install 1 GB, 2 GB, or 4  
GB DIMMs for a total of up  
to 32 GB of memory.  
Each processor’s memory  
controller has three  
memory channels. DIMM  
slots 1, 2, 5, and 6 have  
their own channels; slots  
3 and 4 share a channel  
and slots 7 and 8 share a  
channel.  
If you have  
Two DIMMs  
Three DIMMs  
Four DIMMs  
Six DIMMs  
Fill in these slots  
1 and 2  
For optimal memory  
bandwidth, all six memory  
channels should be used,  
and memory should be  
balanced across the six  
channels.  
1, 2, and 3  
1, 2, and 5, 6  
1, 2, 3 and 5, 6, 7  
1, 2, 3, 4 and 5, 6, 7, 8  
Eight DIMMs  
Note: Populating slot 4 or  
8 slightly drops maximum  
memory bandwidth,  
but depending on the  
applications used, overall  
system performance may  
benefit from the larger  
amount of memory.  
Memory Slot Utility  
If you install different-size DIMMs in your computer, follow the order in the tables above. If the  
DIMM configuration you install doesn’t provide optimized performance, the Memory Slot Utility  
will appear on screen and recommend an improved configuration. To use the Memory Slot  
Utility again, go to /System/Library/Core Services.  
© 2009 Apple Inc. All rights reserved.  
073-1246 Rev. B  
4
 
Removing the  
Installed DIMM  
Because memory DIMMs  
are installed on the  
computer’s processor  
board, before you can  
remove a DIMM, you must  
remove the processor tray.  
1
Locate processor tray.  
2
Press down and  
release 2 latches on  
front of processor tray.  
© 2009 Apple Inc. All rights reserved.  
073-1246 Rev. B  
5
3
4
Holding tray by  
latches, lift it out of  
computer.  
Place tray DIMM side  
up on soft, clean  
cloth.  
Important: When  
removing or installing  
DIMM, be careful of  
nearby heatsink fins, as  
they can be sharp. Always  
handle DIMM only by  
the edges. Do not touch  
its connectors or any  
components.  
5
6
Open ejectors on  
DIMM slot by pushing  
them out to the sides.  
Holding DIMM by  
edges, remove it from  
processor board.  
© 2009 Apple Inc. All rights reserved.  
073-1246 Rev. B  
6
Installing the  
Replacement  
DIMM  
1
2
Align DIMM in slot on  
processor board.  
Push both ends of  
DIMM down until  
ejectors snap back up  
into place.  
Note: If a black sticker  
covers barcode label on  
DIMM you are replacing,  
remove sticker before  
returning DIMM to Apple.  
(Service DIMMs do not  
include black sticker.)  
3
4
Holding processor  
tray by latches, lower  
it back into computer.  
Make sure latches are  
closed flush with front  
of processor tray.  
© 2009 Apple Inc. All rights reserved.  
073-1246 Rev. B  
7
Closing the  
Computer  
1
Replace access panel.  
Note: Make sure  
latch is up before you  
replace panel. If latch  
is down, panel will  
not seat correctly.  
2
Push latch down  
to close and secure  
access panel.  
Warning: Never turn  
on computer unless  
all its internal and  
external parts are in  
place and it is closed.  
Operating computer  
when open or missing  
parts can cause  
damage or injury.  
3
Verify DIMM  
installation using  
“Memory Diagnostic  
LEDs”information on  
next page.  
© 2009 Apple Inc. All rights reserved.  
073-1246 Rev. B  
8
Memory  
Diagnostic LEDs  
Important: The quad-  
core and 8-core processor  
boards include a set of  
diagnostic memory LEDs.  
After re-installing or  
Quad-Core LEDs  
replacing a DIMM, always  
use the LEDs to verify the  
DIMM is correctly seated.  
To verify your DIMM  
installation, do this:  
1
2
3
Start up the  
computer.  
Remove the side  
access panel.  
Check the bank of  
memory LEDs.  
8-Core LEDs  
An illuminated, red  
LED indicates its  
associated DIMM may  
be poorly seated or  
failed.  
4
If you see a red  
LED, refer to“How  
to Troubleshoot  
Memory LEDs”on the  
next page.  
Note: Apple System  
Profiler does not report  
unseated or failed  
memory. You must use the  
memory LEDs to locate  
DIMM issues.  
© 2009 Apple Inc. All rights reserved.  
073-1246 Rev. B  
9
How to  
Troubleshoot  
Memory LEDs  
Follow this procedure when troubleshooting each DIMM identified by a red LED:  
1. Remove and reseat DIMM.  
2. Restart computer. If associated LED is no longer illuminated, issue is resolved.  
3. If associated LED remains illuminated, replace DIMM with new DIMM.  
4. Restart computer and verify LED is no longer illuminated.  
There is one exception. If two LEDs illuminate at the same time for the 3 DIMM and 4 DIMM  
slots or for the 7 DIMM and 8 DIMM slots, check both DIMMs using this process:  
Check  
Result  
Action  
1. Remove both DIMMs identified by  
illuminated LEDs. Set DIMM 4 (or  
DIMM 8) aside, and reseat DIMM 3 (or  
DIMM 7). Restart computer. Is DIMM 3  
(or DIMM 7) LED illuminated?  
Yes  
Replace DIMM 3 (or DIMM 7) with  
new DIMM. Go to step 2.  
No  
Go to step 2.  
2. Reinstall DIMM 4 (or DIMM 8). Restart  
computer. Is one or both LEDs  
illuminated?  
Yes  
Replace DIMM 4 (or DIMM 8) with  
new DIMM.  
No  
Issue resolved.  
 Apple Inc.  
© 2009 Apple Inc. All rights reserved.  
This document is protected under U.S. Copyright Law and International Treaties, and no part of this  
document may be reproduced in any form without written permission from Apple.  
Apple is not responsible for typographical, printing, or inadvertent errors.  
Apple Inc.  
1 Infinite Loop  
Cupertino, CA 95014-2084 USA  
+ 1 408 996 1010  
www.apple.com  
Apple, the Apple logo, and Mac are trademarks of Apple Inc., registered in the U.S. and other countries.  
© 2009 Apple Inc. All rights reserved.  
073-1246 Rev. B  
10  
 

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