High end games fail - which GPU does Parallels emulate?

Discussion in 'Windows Virtual Machine' started by JonathanK8, Nov 13, 2020.

  1. JonathanK8

    JonathanK8 Bit poster

    System setup:
    iMac i7 3.8GHz, 64GB RAM
    Radeon Pro 5700XT, 16GB RAM

    Software failing:
    Microsoft Flight Simulator (MSFS) 2020

    I've been figuring out how to run MSFS on a 2020 iMac. My Mac easily meets the 'ideal' system requirements for the game.

    Parallels standard version is unable to run MSFS because the game requires more memory than the 8GB RAM limit that Parallels places on standard. If you upgrade to Pro, you can increase RAM to pretty much whatever you've got (typically half is recommended). Like this, MSFS will start, no problem.

    You can setup flight plans and jump in a plane. This works really well in clear skies. But if you choose clouds, even the lowest cloud settings, the game hates this. With clouds, Flight Simulator under Parallels Pro flickers badly, flashing all of the clouds on and off 2-5x per second. So 'live weather' (which is gorgeous in game using Boot Camp) is a non-option. If you (or anybody who might accidentally see your screen) suffers from epilepsy, don't go anywhere near this.

    The game developer, Asobo, explains that these flashing clouds are a known issue, affecting older graphics cards, specifically the Nvidia 7XX series. Asobo are not aware of this problem occurring with any other range of graphics cards. And all recent GPUs have no problem at all.

    Does anybody know if (1) does Parallels Pro directly address the graphics card in my iMac, or is it creating its own virtual GPU emulator?, (2) if Parallels Pro is emulating a GPU, does anybody know when this was last updated? it seems to be emulating a virtual Nvidia 7XX. Which is pretty old now.

    This would explain why Parallels is starting to struggle with the current generation of Windows games. Please update this, so that Parallels can cope with current games...
  2. ChristianK34

    ChristianK34 Bit poster

    5700XT via Parallels is probably not enough. I put a 6900 in an eGPU and I think any 6000-series would do nicely.

    The key with Flight Simulator is it's a RAM *hog*. SO MUCH RAM. By which I mean GPU RAM, not the computer. And yes I know about Parallels graphics memory, but what I'm doing it monitoring my Mac's GPU RAM usage during gameplay while MSFS is running inside Parallels. The GPU processor is barely tapped, but the GPU memory goes up.

    GPU memory particularly spikes during loading of the flight, after you've completed the long startup and menus and selected a game. It's the final loading screen that really sees the memory jump up 2x and 3x more. Generally it'll want to sit near the limit, which is fine, but it needs to be a high enough limit. Remember this game is simulating ALL OF PLANET EARTH as much as any game has ever done in history, so it'll really go for it; there are naturally mitigations for limits but a practical minimum you'll need is a 6000-series GPU.

    It's the 16 GB of GPU RAM that really helps. (Physical GPU, which Parallels' virtual display driver will soak up on your game's behalf).

    For some reason, there are areas of MSFS's planet earth that overload the limit of GPU RAM, probably due to memory leaks in a peculiar way. I'm thinking in particular of the world's highest airport, ZUDC in China (Tibet?), and while the airport itself loads and renders fine (with or without enhancement packs), it's the landscape nearby that overloads the simulator, whether within Parallels or Boot Camp. Thankfully, with Parallels it just crashes the app; with Boot Camp you get a blue screen of death (BSOD), which crashes Windows entirely. Try this: Fly ZUDC to ZUDC, so it does a loop, and use AI pilot to do everything (maybe cut your payload and fuel to minimum so you can take off in thin air). Then you'll probably end up flying over the tundra plateau, which looks harmless enough and featureless too ... but hidden deep in that data is something strange that overloads the simulator. Without 16 GB of GPU RAM, the whole thing just stutters at best, crashes at worst.

    With this odd mix of tolerance for GPU processing but need for GPU RAM, I've found the following settings recommendations work best:
    - most things can stay on "Ultra", except:
    - "Terrain Level of Detail" keep that down to 100, maybe try 150 if brave
    - "Off Screen Terrain Pre-Caching" just set to minimum, for some reason, everything else is worse
    - maybe: V-Sync On, 33% limit; worth a try, if you're sticking to 60fps overall and/or mixing with other tasks
    - switch a few other things up to maximum (beyond default "Ultra"), especially cloud detail
    - similarly, stuff like AMD texture rendering are "free", so push those to 200%
    - then finally go to Full Screen and choose an overall resolution to drive the sim at. 1080p, 1440p, 2160p, according to your system's total performance

    I keep "Render Scaling" at 100% but just tweak "Terrain Level of Detail" instead, since it does an equivalent thing but with far more effect.
    If you feel like tweaking anything beyond 100% then tweak that one.

  3. ChristianK34

    ChristianK34 Bit poster

    After sharing the advice above, I've been looking into it in case I'm wrong, both in Boot Camp and Parallels.

    My new advice is similar but simpler, in 3 steps:

    1. Top settings: Same as Boot Camp.
    • If your card can handle 4K then MSFS won't improve at 1440p or 1080p. Go as high as your GPU is normally good for games, maximum 4K.
    • Full Screen, TAA, Scaling 100, FidelityFx 200, V-Sync On, 100%, DX11.
    2. Choose a Global Rendering Quality and try each for performance, then make the Step 3 tweaks below.
    • For Parallels I choose "Low", or just go 2x presets lower than Boot Camp (for me is "High").
    3. The following tweaks improve the results over the presets noticeably, far more than lowering performance:
    • Volumetric Clouds = Ultra ... there's a bad clouds bug causes stripes, especially in thin clouds
    • Texture Resolution = High
    • And probably Off-Screen Terrain Pre-Caching ... reduce to Low, actually improves performance with no side-effect IMO, YMMV.
    Probably restart the app for a proper assessment.
    MSFS even gives a warning for tweaking Texture Resolution without restarting, but there's a bug since it doesn't warn if you change that setting via a preset, yet still warns you if it hasn't changed after a preset choice plus making the individual setting the way it was before.

    "Texture Resolution" gives more realism bang-for-buck than Terrain/Objects "Level of Detail" sliders, and I think the rest of the presets work together with those two sliders to actually deliver the frames per second. While I can absolutely see what those sliders deliver, it's no good trying to experiment for a balance of performance with those sliders: Just use the presets for that, and once you have the raw performance, make the tweaks to improve quality without hurting performance.

    I do love pushing the Terrain Level of Detail to crazy high 400, if I'm doing photography simulation for instance ... setting up a drone on a hill, dialing in some clouds and a sunset, for instance. That's when you're playing Earth Simulator haha!

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