G5 RAM Question - mixing DIMMs

Discussion in 'Buying Tips, Advice and Discussion (archive)' started by Skiniftz, Jul 30, 2004.

  1. Skiniftz macrumors 6502

    Joined:
    Jan 18, 2004
    #1
    I just got a DP2.0 off the shelf with 512Mb (2x256Mb DIMMS)

    I'm just about to order my extra RAM, but need to know can I mix DIMM sizes - eg. could I install 2x1Gb DIMMS along with the 2x256Mb DIMMS and have 2.5Gb or would this cause some problem?

    I can't see why it would but I seem to recall reading somewhere that if you use 1Gb DIMMS then you cant use anything smaller, however I've not seen anything to back this up.

    Anyone know any better?
     
  2. Macmaniac macrumors 68040

    Macmaniac

    #2
    Its fine to mix and math as long as the pairs of DIMMs are the same size. Having a 256 and a 1 gig stick paired together would be very bad.
     
  3. Skiniftz thread starter macrumors 6502

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    Jan 18, 2004
    #3
    Thanks. :)
     
  4. slughead macrumors 68030

    slughead

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    Apr 28, 2004
    #4
    It's off topic but I love your sig, Skiniftz

     
  5. Skiniftz thread starter macrumors 6502

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    Jan 18, 2004
    #5
    Heh - thankyou. Just a shame it exists really!
     
  6. musicpyrite macrumors 68000

    musicpyrite

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    Jan 6, 2004
    Location:
    Cape Cod
    #6
    Why would that be?

    And do I have to buy RAM that are sold in pairs? Like it says 1GB of RAM, but actually its 512x2.
     
  7. slughead macrumors 68030

    slughead

    Joined:
    Apr 28, 2004
    #7
    no I don't think it has to be sold in pairs.

    It's kind of like RAID 0 (striped), Dual channel uses both Ram Buses combined to make the computer faster. Therefore you need the same brand and size.

    [EDIT: I bought two single chips for my PC's Dual Channel and they work just fine.. In fact, my PC crashes less than my mac does ... I'm scared.]
     
  8. quarkman97 macrumors newbie

    Joined:
    Aug 25, 2003
    #8
    We just got a refurb G5 1.6 Ghz in at work.

    The G5 came with (2) 128 MB PC2700 DIMMs in it.

    Mac Warehouse shipped us (1) 512 MB PC3200 DIMM.

    I knew right away this wouldn't work since I needed have paired memory.

    My question is: could I get another 512 MB PC3200 DIMM and pair it with the other 512 MB at PC3200?

    Would this jive since once pair is at PC2700 and the other is at PC3200? IIRC, I remember reading something that the 3200 would slow to the 2700 clockspeed.

    Thanks for the help in advance.
     
  9. numark macrumors member

    Joined:
    Jul 24, 2004
    Location:
    Buffalo, NY
    #9
    Yes, you can add another PC3200 stick to the machine and have it work. The speed quoted for memory is merely its highest-rated speed. The manufacturer says it will work up to a certain speed guaranteed. You can always run it at a lower speed.
     
  10. keysersoze macrumors 68000

    keysersoze

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    Jan 6, 2004
    Location:
    NH
    #10
    I tried putting 2x128MB PC3200 in my Refurb G5 1.6 and had a tremendous number of kernel panics. The RAM worked fine in the new Dual 1.8 G5 it had been pulled from, but it screwed my machine. I will never put PC3200 in it again.
     
  11. quarkman97 macrumors newbie

    Joined:
    Aug 25, 2003
    #11
    Good to know, keysersoze. We have the 1.6 Ghz as well. I've read a little bit while doing a search for this about all the memory problems with the original G5's.

    I'll send back the 512 and get two, 256's.
     
  12. keysersoze macrumors 68000

    keysersoze

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    Jan 6, 2004
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    NH
    #12
    and make sure they are the PC2700... ;)
     
  13. quarkman97 macrumors newbie

    Joined:
    Aug 25, 2003
    #13
    Well, sorta bad news.

    The boss already ordered a PC3200 512 MB stick and it should be here today.

    I told him that it would be risky, but he said do what you gotta do. If it's cranky, we'll order two PC2700 DIMMs.

    I'll keep an eye on it and post my results here.

    <crosses fingers>
     
  14. garybUK Guest

    garybUK

    Joined:
    Jun 3, 2002
    #14
    G5's are REALLY funny about what ram you put in, i've tried corsair and kingston with really bad Kernel Panics.

    The only stable ram I have been able to get it working with properly is Crucial and Samsung's. I always recommend buying them in pairs, Crucial.com/uk will ship x2 of the identical ram, i put x2 512mb's PC2700's in my Dual 1.8 along with the stock samsung x2 256mb's PC2700's
     
  15. keysersoze macrumors 68000

    keysersoze

    Joined:
    Jan 6, 2004
    Location:
    NH
    #15
    Please do let us know how it turns out. My case could be isolated- it would be nice to be proved wrong. Things you should watch out for:

    1) Computer freezing up needing a hard reboot
    2) Grey screen appears that needs a hard reboot
    3) Non-responsive keyboard/mouse

    Good luck :)
     
  16. keysersoze macrumors 68000

    keysersoze

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    Jan 6, 2004
    Location:
    NH
    #16
    I thought all Dual 1.8's took PC3200? Am I wrong? :confused:
     

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