Parallels fails to run Flight Simulator - how to remove memory limit?

Discussion in 'Windows Guest OS Discussion' started by JonathanK8, Nov 11, 2020.

  1. JonathanK8

    JonathanK8 Bit Poster

    Parallels Pro v16
    iMac i7 3.8GHz 8 core, 72GB RAM
    GPU AMD Radeon Pro 5700XT, 16GB RAM
    Windows 10

    Microsoft Flight Simulator (MSFS) 2020

    PARALLELS - Fail

    QUESTION/SUGGESTION - Parallels standard limits the RAM available to the Windows virtual machine. After chatting with your tech support guys, I upgraded to Parallels Pro which removes this RAM limitation. I can now allocate plenty of RAM to the VM... but it appears that I can only effectively allocate max 2GB RAM to my graphics cards, which has upto 16GB available.

    With Parallels Pro, I used to be able to start and run Microsoft Flight Simulator (MSFS). Until last week.

    The problem is that Microsoft/Asobo issued a patch last week which 'enhanced the clouds'. This update triggers low end graphics cards (the ingame zendesk team specifically mentions the Nvidia 7XX series) to flash any clouds on and off at about 2-5 times per second. Great if you want to experience epilepsy. Not so good if you plan on enjoying the game without a headache.

    How do we enable Parallels/Pro to access the full facilities of the GPU? It has 16GB RAM (and is listed as 'ideal' on the game tech spec requirements) so Parallels' 2GB limit is really troublesome...
    GustavoS3 likes this.
  2. alev

    alev Parallels Developers

    Hi Jonathan,

    Please set the video memory option in VM configuration to Auto, it will then allow Windows to use up to half of RAM allocated to VM. If you have 32GB allocated for Windows, then 16GB can be used for video purposes.

    No Mac application has direct access to GPU memory or its allocation.
  3. JonathanK8

    JonathanK8 Bit Poster

    Thanks @alev , I'll give that go and report back...
  4. JonathanK8

    JonathanK8 Bit Poster

    Hi again @alev, ok, as you recommended I switched the Hardware/Graphics/Memory option to 'Auto (recommended)' and significantly increasing the Hardware/CPU & Memory resources available to Parallels, to 8 processors and 48GB. The MSFS game runs fine in clear skies. But as soon as clouds are seen, the clouds flicker on and off, at 2-5x per second.

    Question: does Parallels utilise my GPU? it's a high end Radeon 5700XT, which has no difficulty handling MSFS, even on Ultra settings, using Boot Camp.

    MSFS explain that the flickering or flashing clouds problem began last week, and only affects the (now rather old) Nvidia 7XX graphics cards. If Parallels is employing a virtual simulator of a 7XX GPU, instead of addressing the machine's own graphics card, this would explain the issue.

    The solution would be for Parallels to update its GPU simulator to a newer chip. The 7XX is very old now...
  5. MattF6

    MattF6 Bit Poster

    Thanks JonathanK8 and alev for your feedback
    I have read and tried all the suggestions
    above and i cant get MSFS to even play
    Parallels Pro v16.1.1 (49141)
    iMac i5 3.GHz 6-Core, 32 GB 2667 MHz DDR4
    GPU AMD Radeon Pro 580X 8 GB
    Windows 10 Pro

    Microsoft Flight Simulator (MSFS) 2020

    PARALLELS - Fail

    The settings for CPU & memory. AND Graphics are shown below. Ive checked all that was suggested above

    Screen Shot 2020-12-14 at 9.09.03 pm.png

    Screen Shot 2020-12-14 at 9.10.22 pm.png

    Attached Files:

  6. AdamP14

    AdamP14 Bit Poster

    I have the same problem
    I changed all like on the pic but still doesn't work
  7. StaffanO1


    Hello Matt. I have almost the same computer as you (but less ram and may graphics card is 570X 4GB).
    I'm just curious if you found a solution to this. I am planning to buy MSFS if I can run it on my iMac.
    So did you use Parallels after all or maybe using BootCamp?
    And what type of joystick is working on Mac with MSFS?
  8. Christian63

    Christian63 Bit Poster

    I tried Parallels 17 (related to Bootcamp) and in Flight Simulator 2020, some images are strange. Clouds for example. I think it does not use the capacity of the graphics card (radeon PRO 5500 XT 8 GB). That's why I'm not buying Parallels right now while waiting for a solution.

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