256MB less RAM in Snow Leopard

Discussion in 'macOS' started by glenncal, Aug 22, 2009.

  1. glenncal macrumors member

    Joined:
    Jun 7, 2009
    #1
    My installation of Snow Leopard is reporting that I have 1.75GB of memory under the pie chart representation in Activity Monitor. It seems that Snow Leopard is using more wired memory than the Leopard, making it unavailable to the system. I do understand that the Snow Leopard build I'm using might not be the final one, but I've found other users experiencing this throughout the web without any resolution/explanation.

    So what do you think? Is anyone else here using Snow Leopard having less RAM being reported in Activity Monitor? Is this a bug, or is the RAM being used by the OS?

    PS. Yesterday I posted this thread here but a moderator merged it with the thread I'd posted in the MacBook Pro forum. If this is felt to be necessary in this thread, I'm sorry. However, I do believe that the place for this thread is in the Mac OS X forum. The thread in the MBP forum was posted when I thought that the problem was with my MBP but it now seems clear that the problem is with Snow Leopard, hence the different threads (And if the threads were to be merged, it'd make more sense to merge the other one into this, in my opinion).
     
  2. kryptonianjorel macrumors 6502

    Joined:
    Jul 3, 2009
    #2
    Well knowing that its a MBP tells me that it must have something to do with your video RAM. Your system is probably taking 256 for video RAM and as such it doesn't show up as system RAM
     
  3. glenncal thread starter macrumors member

    Joined:
    Jun 7, 2009
    #3
    That's what I initially thought but ruled out for 2 reasons:
    1) Leopard lists the whole 2GB, and has more free memory overall.
    2) As far as I know the 9600M should have 256MB dedicated RAM. Here, this is occuring both when using the 9600M and the 9400M.

    Edit: To be exact, a clean install of Leopard used around 200MB wired memory on startup, while a clean install of Snow Leopard uses around 400MB. These 256MB are not counted up in the total memory listed under the chart. Furthermore, despite the fact that SL currently lists 460MB of wired memory in Activity Monitor, only 200MB of wired memory is listed as being used in the istat widget.
     
  4. ayeying macrumors 601

    ayeying

    Joined:
    Dec 5, 2007
    Location:
    Yay Area, CA
    #4
    Regardless if you're in 9600M or 9400M, the 256MB shared ram will be used. That's just how it is designed. You won't regain that 256MB if you're using the dedicated video card vs the shared.
     
  5. glenncal thread starter macrumors member

    Joined:
    Jun 7, 2009
    #5
    That makes sense, but if true I still don't know how those 256MB of RAM are not used in Leopard .. I don't know what the normal amount of "Wired memory" is upon startup but 450MB seems high when compared to Leopard's 200MBs
     
  6. Eidorian macrumors Penryn

    Eidorian

    Joined:
    Mar 23, 2005
    Location:
    Indianapolis
    #6
    Snow Leopard might actually show the available system RAM after the allocation to the IGP.

    It's still allocated in Leopard but it's not represented in Activity Monitor as having less RAM to begin with.
     
  7. glenncal thread starter macrumors member

    Joined:
    Jun 7, 2009
    #7
    Thanks ayeying and Eidorian. A final question to ayeying just to clarify everything, seing as you're running SL on a MB: You get 1.75GB listed in activity monitor too, right?
     
  8. ayeying macrumors 601

    ayeying

    Joined:
    Dec 5, 2007
    Location:
    Yay Area, CA
    #8
    Yes. Both SL and Windows 7 have a more accurate reading of actual usable ram.
     
  9. dukebound85 macrumors P6

    dukebound85

    Joined:
    Jul 17, 2005
    Location:
    5045 feet above sea level
    #9
    op, your system profiler should tell you the total ram you have installed and activity monitor should tell you total ram usable
     
  10. Rubel macrumors newbie

    Joined:
    Aug 22, 2009
    #10
    Yes, it's a bit startling to go from Leopard telling me all 4 gigs on my iMac are usable (x1600 video, so no RAM sharing) to having Snow Leopard tell me I've just got 3 gigs. (As you say, System Profiler reports the correct physical RAM, but Activity Monitor and top report one less gig.) Sob! Oh well. I guess it's all getting used for something.
     
  11. ayeying macrumors 601

    ayeying

    Joined:
    Dec 5, 2007
    Location:
    Yay Area, CA
    #11
    Your system only allows 3GB usable. If you add up the numbers, it'll be 3GB, not 4GB. SL just reads it correctly so you don't have to do the work manually.
     
  12. fr4b3lo macrumors newbie

    Joined:
    Apr 14, 2010
    #12
    256 not disapear in a mac pro

    Now i test with snow leopard on a MAC PRO and this 256 GB less dont happen in this computer. I think that only happen in Mac book pro's that using 9400 and 9600 nvidia cards...
     

Share This Page