i Mac and Parallels

Discussion in 'iMac' started by hcpa, Jan 26, 2011.

  1. hcpa macrumors newbie

    Jan 26, 2011
    Hi everyone I need help.
    I bought a IMAC i7 with 16 gb. Since I need to work with windows software, I installed Parallels for virtualization. In the hardware settings there is an option to choose how many CPU's to use in VM. What would you recommend for running windows in the most efficient way?
    I can choose from 1 to 8 CPU's what does this mean?

  2. simsaladimbamba

    Nov 28, 2010
    The i7 iMac has four cores, which allow 8 threads, and therefore show up as eight CPUs in Parallels.

    Depending on what you don in Windows as a VM, you can assign two, four or eight cores to that VM.
    If you only run Notepad or IE or another text based application, two "CPUs" should suffice. If the application is more intensive, more assigned "CPUs" might help.
    Btw, if you use a 32-bit version of Windows, there is no need to assign more than 3.5GB of RAM to that VM. If it is a 64-bit version of Windows, you can assing more RAM if needed.
    I hope you didn't buy the RAM via Apple, as Apple takes 800 USD more than MacSales for that.

    Helpful Information for Any Mac User by GGJstudios

    PS: It is called and named "iMac". >>> www.apple.com/mac
  3. hcpa thread starter macrumors newbie

    Jan 26, 2011

    I am using Rhinoceros, so I am going to give 8GB and 4 CPU's to the VM. i think that with that I will be OK. Any Ideas?
  4. coolspot18, Jan 26, 2011
    Last edited: Jan 26, 2011

    coolspot18 macrumors 65816

    Aug 16, 2010
    For Windows 7:

    PCs with multi-core processors:
    Windows 7 was designed to work with today's multi-core processors. All 32-bit versions of Windows 7 can support up to 32 processor cores, while 64‑bit versions can support up to 256 processor cores.

    PCs with multiple processors (CPUs):
    Commercial servers, workstations, and other high-end PCs may have more than one physical processor. Windows 7 Professional, Enterprise, and Ultimate allow for two physical processors, providing the best performance on these computers. Windows 7 Starter, Home Basic, and Home Premium will recognize only one physical processor.


    So in your case, assigning 4 CPUs is a against the EULA (not even sure if it'll work in Windows 7) - instead assign 2 CPUs and X cores to each CPU.
  5. ndraves macrumors member

    Jan 19, 2011
    In Parallels it asks you for number of CPU's this refers to the total number of processor cores you wish the VM to run, not how many physical processors. Windows will still recognise it as one physical CPU.

    With a quad i7 you just need to make sure you give the power to where you need it. the more you give to windows the faster it'll run but the OSX will slow like crazy. So your choice, maybe have set it at something and have a go. It's easy to change on rebooting the VM.
  6. talmy macrumors 601


    Oct 26, 2009
    If you are only running one application in Windows and it doesn't take advantage of multiple processor cores, then it doesn't make sense to allow more than one core to Parallels. As a test, go ahead and allocate two cores then look at the task manager in Windows to see if you can drive them both beyond 50% each with the program(s) you run.

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