RRScrewdriver
Level 1 (4 points)
Desktops

Q: Memory Upgrade Mac Pro 3,1

Hello all. I am looking into upgrading my memory in my Mac Pro. In the screen shot below, you can see the section of the apple support page that you get when you click on upgrade instructions in the memory tab in System information.

 

In this page it says my computer uses 800 MHz DDR2 memory. However in my System Information window it tells me I have 667 MHz installed.

 

I have three questions:

 

1. Which memory is the correct one to buy?

2. Am I seeing degraded performance with my current memory?

3. Can I just add another 8GB or do I need to replace it all with 800MHz?

 

Screen Shot 2016-09-29 at 11.52.42 PM.png

OBS Mac Pro (Early 2008), OS X El Capitan (10.11.6)

Posted on Sep 29, 2016 11:24 PM

by kaz-k,Solvedanswer
kaz-k kaz-k
Level 5 (5,975 points)
Desktops
A:

1) 800 MHz DDR2 memory is your memory.

2) Yes.

3) Yes, replace all memory to 800 MHz DDR2 memory, though it's not that performance increase, I suppose, so it's OK to upgrade another 8GB 667MHz memory sticks.

Posted on Sep 30, 2016 10:04 PM

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RRScrewdriver

Q: Memory Upgrade Mac Pro 3,1

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  • by kaz-k,Solvedanswer

    kaz-k kaz-k Sep 30, 2016 10:04 PM in response to RRScrewdriver
    Level 5 (5,975 points)
    Desktops
    Sep 30, 2016 10:04 PM in response to RRScrewdriver

    1) 800 MHz DDR2 memory is your memory.

    2) Yes.

    3) Yes, replace all memory to 800 MHz DDR2 memory, though it's not that performance increase, I suppose, so it's OK to upgrade another 8GB 667MHz memory sticks.

  • by lllaass,

    lllaass lllaass Sep 30, 2016 10:04 PM in response to RRScrewdriver
    Level 10 (190,677 points)
    Apple Watch
    Sep 30, 2016 10:04 PM in response to RRScrewdriver

    Sounds like someone install memory meant for a 2006-2007 (1.1 and 2.1) Mac Pro in your Mac since those earlier ones used the slower memory. The Mac will use the slower memory by slowing down the memory bus.

    If you now ADD some correct 800 memory it will run at 667 since you have some of the slower memory installed.

     

    Make sure you get memory made for the Mac since those have the large heat sinks and temp sensors the Mac requires. Also, kt is not clear if you are using ECC memory. Click on the memory tab in the window in the upper right screenshot you posted. The Mac Peo can use either ECC (Error Correcting Code) memory or standard memory but the two different types cant' be mixed

     

  • by kaz-k,

    kaz-k kaz-k Sep 30, 2016 1:28 AM in response to RRScrewdriver
    Level 5 (5,975 points)
    Desktops
    Sep 30, 2016 1:28 AM in response to RRScrewdriver

    https://eshop.macsales.com/tech_center/manuals/Memory/macpro.pdf

  • by RRScrewdriver,

    RRScrewdriver RRScrewdriver Sep 30, 2016 10:08 PM in response to RRScrewdriver
    Level 1 (4 points)
    Desktops
    Sep 30, 2016 10:08 PM in response to RRScrewdriver

    Thank you for all the prompt relies.  Upon further examination he also installed the second set of DIMMS in the wrong slots (all memory sticks were in the top riser.  I moved the ram around and it doesn't seem to make any performance difference. ECC is enabled but I think I will just put in 8 new sticks and be done with it.