Batman AC negative CFX scaling with hybrid Physx

Discussion in 'Videocards vs General Purpose - NVIDIA Ageia PhysX' started by automaticman, Jan 18, 2012.

  1. automaticman

    automaticman Master Guru

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    GPU:
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    So I've been fooling around with my new build and Playing Arkham City. I'm using a pair of 6950 1gb in CFX and just swapped out a gt430 with a friend's 9800gt dedicated to hybrid PhysX.

    At 1920x1200, DX11, Physx high, normal tesselation, fxaa high and all other settings at their highest I'm seeing around 50fps avg on the benchmark with crossfire disabled, but only 38fps with crossfire enabled. Max is 72 either way.

    I have a second monitor showing the desktop with various monitoring tools, so I can see that I am getting usage on both GPUs (although only about 40%), as well as usage on the 9800gt for physx. Without crossfire, the single 6950 shows around 90% usage.

    Unfortunately I can't compare to what I was getting using the gt430 for physx because I didn't realize hybrid physx wasn't working (turns out the newest physx sw 1107 doesn't work with 1.05ff mod).

    I was running physx high on my 2500k without realizing it and only really losing a few fps, which odd enough, is pretty inline with other reviews.

    So anyways, anyone else have a CFX with hybrid physx setup and seeing the same negative scaling?
     
  2. automaticman

    automaticman Master Guru

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    OK, so I ran a slew of benchmarks this morning and came up some interesting numbers. Also, for the record, I do have the dx11 patch installed for the game.

    For these benchmarks the only thing I'm changing is DX11 on/off (with dx 11 on I have features set to MVSS and HBAO, and tessellation on normal), crossfire on/off (via modifying the game profile in 12.1), and physx off/high.

    Resolution is 1920x1200, FXAA at high, everyhting else turned on or very high for detail.

    So first round - Physx OFF, DX9

    crossfire off
    min 62
    max 127
    avg 103

    Crossfire ON
    min 71
    max 170
    avg 137

    Decent scaling here, no stuttering

    next round - Physx OFF, DX11

    Crossfire off
    min 20
    max 83
    avg 68

    Crossfire ON
    min 26
    max 108
    avg 70

    Really pretty crap scaling here, seeing a little bit of the stuttering that the patch was supposed to fix. DX11 really kills any kind of crossfire scaling it seems.

    No let's turn on Physx - Physx HIGH, DX9

    Crossfire off
    min 20
    max 99
    avg 53

    Crossfire ON
    min 20
    max 96
    avg 54

    Again, no scaling. I guess I'm just maxing out the 9800gt here. I will say that with crossfire on the benchmark felt smoother and the min was at 30 up until right when the ice shard phase started (fps came right back up but there was a dip right at the beginning). With one card the min was down at 20 pretty much from the get-go. I think I'll be playing the game with these settings.

    Last we have Physx HIGH, DX11

    Crossfire off
    min 18
    max 72
    avg 49

    Crossfire ON
    min 13
    max 96
    avg 41

    Here we see the negative scaling, and an annoying amount of stuttering. And really, the dx11 effects just arent that noticeable. Yeah the tessellation is ok, but I'd rather have physx on.


    Ideally I'd re-install the gt430 for physx and see how it compares to the 9800gt, but I already installed it into my wife's computer and had to fight for about 15-20 minutes to get the HDMI cable plugged in. I may still try it, but not today.


    Really the most telling number for me was the dx11 crossfire scaling without physx. I mean with physx on, it's not hard to just imagine that the 9800gt is bottlenecking the fps, it can only go as fast as that card can process the physx. But with the physx turned off and to still see almost no scaling with dx11 was pretty disappointing.

    I don't know if the issue is with the AMD driver or the games coding (not surprising given the issues this game has had).
     

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