Windows 8 high idle VRAM usage

Discussion in 'Windows OS and Software' started by octiceps, Sep 17, 2014.

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  1. octiceps

    octiceps Nimrod

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    [​IMG]

    Wow. So almost 25% of the GTX 690's 2GB frame buffer is used by Windows 8 just when idling at 4K. And it uses way more than Windows 7 (over 2x at 1080p!) despite missing marquee Aero features such as Glass translucency/blur and Flip 3D. I have a strong feeling it's Metro and/or WDDM 1.3 hogging all that VRAM.

    This means Windows 8 is not a good OS for high-res gaming (e.g. 4K, surround) because the amount of VRAM that Aero/DWM uses is directly related to screen resolution. In Windows 7, you can free up all that video memory by disabling Aero, but there's no way to do it in Windows 8 since DWM is required for Metro and apps to function.

    I'm not sure if Windows 8 automatically unloads the occupied VRAM as needed if it detects that a game or other app requires more. Or if it automatically disables desktop composition when running fullscreen games as Windows 7 is supposed to do but almost never does. But we can't test any of this because Windows 8 doesn't allow us to flip Aero on/off.

    High Res Gaming. Do you have Aero Disabled? You should. Pics because it did happen. - EVGA Forums

    You'll notice per above that disabling Aero in Windows 7 raises FPS across the board in addition to freeing up hundreds of MB's of VRAM. Since most games not named BF4 (an edge case due to DX11.1 CPU optimizations) perform the same on both OSes, it's safe to assume that disabling Aero in Windows 7 gives it an edge in performance over Windows 8.

    Another benefit of Windows 7: Windowed gaming. DWM enforces V-Sync for games running in windowed or borderless windowed mode, causing mouse lag and stuttering/performance issues. Desktop composition can be disabled globally or on a per-app basis in Windows 7 but not in Windows 8. So Windows 7 is the way to go for streamers/ALT-TABers, surround monitors, emulators/old games, and anywhere else you need to game in a window.

    TL;DR Windows 7 is a better gaming OS than Windows 8. :D
     
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  2. HTWingNut

    HTWingNut Bacon

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    Good information. That is strange. 258MB used just to run a 1080p screen with basically a non-3D UI? I'd like to see what is being used by that vRAM.
     
  3. Ajfountains

    Ajfountains Notebook Deity

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    Strange indeed. I imagine my 675mx would struggle at 1080p in windows 8, despite it having 4gb of vram. I'm also sure I wouldn't be able to have my dreamscene background in Win 8 either. Any idea if dreamscene even works for win 8?
     
  4. octiceps

    octiceps Nimrod

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    My unscientific stab-in-the-dark is that the VRAM is being reserved by Metro (for smoother app switching and UI transitions?) and/or due to changes in WDDM 1.3.

    I think you'll be fine, this is mainly a concern for people with 2GB or lower cards.
     
  5. alexhawker

    alexhawker Spent Gladiator

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    I'd like to know how to measure this. My card is 2GB and my screen is 3200x1800...

    Edit - found it in GPU-z. Currently 344Mb on an external monitor @ 1680 x 1050.

    Will restart and see what I get on the internal screen only and without the browser open.

    284Mb for just the internal screen. 179Mb for just the external monitor, 316 for both.
     
  6. alexhawker

    alexhawker Spent Gladiator

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    In other words, the numbers in the graph above seem inflated for win 8.1. Bad drivers maybe?


    Sent from my iPad using Tapatalk
     
  7. baii

    baii Sone

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    500MB with a 1440p and a 1080p. easily break 3GB running dead rising 3. I think it did hover to 800MBish on my setup with just windows.

    used to have 4Gb on k5000m so no biggie, but now only 2 gb with m6100. More reason to play less games I guess.
     
  8. Dufus

    Dufus .

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    Where's this link from and what is considered idle, how where the measurements taken?

    Correct me if I'm wrong here but "frame buffer" is just the memory used for the display and in a muxless system with switchable graphics is controlled by the iGD, but I think maybe you are using it in the context of all VRAM. Other things use VRAM also. For example, loading big textures one can easily use Gigabytes of VRAM with just a 4 by 4 pixel window to display them.


    Well here's some numbers from my 765M VRAM usage.

    W8.1, normal GUI screen at 1920 x 1080, idle VRAM usage 62MB. Running a 3D app fullscreen, 230MB.

    W7, normal GUI screen at 1920 x 1080, idle VRAM usage 57MB. Running the same 3D app fullscreen, 227MB.

    Might be different drivers, forgot to check.
     
  9. octiceps

    octiceps Nimrod

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    Desktop GTX 690, no iGPU. Taken from here: Debunking Common Myths About Video Memory - Tom’s Hardware

    On the second page:

     
  10. Dufus

    Dufus .

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    Here's using Desktop GT640 2GB, no iGD.

    1400x900, idle GUI.
    W7 Aero VRAM 60MB reserved, 41MB used, 13MB shared. Killing DWM in basic gets back ~30MB
    W8.1 VRAM 60MB reserved, 48MB used, 12MB shared.

    Note that you can use more than VRAM limit by swapping out to DRAM, bit like using the pagefile but not as harsh on the performance hit. As for gaming performance on each OS, best IMO to run the game itself and judge by the results.
     
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