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Graphics Two Nvidia cards in SLI - still need a dedicated card for PhysX?

Discussion in 'Hardware' started by mikemorton, 27 Nov 2010.

  1. mikemorton

    mikemorton Minimodder

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    If you have two cards in SLI, will they naturally absorb the demands of PhysX, or would you still need a dedicated card?

    This is a hypothetical high-end gaming scenario.

    For example, say you had two GTX 480s in SLI.

    And if you did want a third card, what sort of motherboard would you need that could cater for three cards?

    TIA

    Mike
     
  2. DragunovHUN

    DragunovHUN Modder

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    One that has three full length slots (16x physical, at least 8x electrical) and supports at least two-way SLi.
     
  3. Ph4ZeD

    Ph4ZeD What's a Dremel?

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    You do if you allow nVidia to brainwash you.
     
  4. Teelzebub

    Teelzebub Up yours GOD,Whats best served cold

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    You need a mobo with three slots although if you've got two 480's in SLI you really dont need a dedicated physx card.
     
  5. mikemorton

    mikemorton Minimodder

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    LOL!

    Yeah, but ain't it pretty, seeing all that broken glass and bits of chunks of brick wall flying everywhere. :D
     
  6. Ph4ZeD

    Ph4ZeD What's a Dremel?

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    Let's face it though mate, most games dont support it. Blizzard and Valve are the biggest players in the PC game Market and they don't seem interested.
     
  7. padrejones2001

    padrejones2001 Puppy Love

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    I agree with Ph4ZeD, PhysX is technological equivalent of snake oil. I say don't bother.
     
  8. memeroot

    memeroot aged and experianced

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    if you have 2 480's there are few games that will hit that - but yes - a card will help

    tomshardware did a good overview
     
  9. sandys

    sandys Multimodder

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    Yup a dedicated card does help even if you have dual sli as mentioned quite a few articles on it toms hardware being once such place or firing squad, hexus.

    Not really needed if you have some grunt, I'm still running 8800gt sli and it takes the load of these to give me more performance.
     
  10. Bakes

    Bakes What's a Dremel?

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    It helps, but it's totally unnecessary with 2x GTX 480s (at any resolution). If the price of the dedicated PhysX card is a new motherboard as well, it's even more unnecessary.

    Also: OP - you never need a dedicated PhysX card in all but the most extreme situations (and you've been brainwashed by nV if you believe it). My 580 plays the few PhysX games I play just fine, at 2560x1600, with full PhysX effects.
     
  11. Ph4ZeD

    Ph4ZeD What's a Dremel?

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    OK I'll be honest about PhysX. I know I'm known as a PhysX hater. I think in principle, it's a great idea. Im an enthusiast, so I believe in pushing the limits of what is possible, even if it seems frivolous or trivial. But PhysX wont take off. Physics in games will, I'm sure of that. But PhysX wont. Why? Because nVidia have a serious conflict of interest. Its in their interest to push pc gaming, and to destroy their competition, ATi. So they make sure their little pet project runs gimped on CPUs and ATis GPUs even when it could run a treat. Which is a real shame.
     
  12. wyx087

    wyx087 Homeworld 3 is happening!!

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    if you are already running on a meaty nvidia GPU (or two) then there's no reason to try to buy another one JUST for PhysX.

    i've bought a 8800GT for physx when i had ATI cards, found it to be more trouble than it's worth. the physx card will idle there for 90% of the time, wasting power without doing anything. it's best to just relay on the single meaty GPU to handle everything.
    (although i am a known multi-GPU hater, i believe in getting a single powerful GPU for everything, and save on electricity bills)

    in the end, it's how much physx is worth to YOU. if you feel it's worth the cost of card AND electricity bill to run it uselessly over 90% of your computer ON time, then go for it. otherwise stick with a single most powerful GPU.
     
  13. sandys

    sandys Multimodder

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    Indeed to me it was worth it, I've pretty much given up on PC gaming, as a lot of multiformat games end up gimped on PC (due to console bias so have dodgy control, graphics etc.) so I pick them up on console, but something like Physx is one of the few reasons I might choose to buy on PC instead, things like Batman lacked half the atmosphere on console, all the Physx smoke etc, make it a different and better game.

    Most of the games I;ve actually decided to turn my PC on for (that aren't racers ) were because of Physx, as much as people scoff at Nvidia at least they are trying to do something different for PC gaming beyond a higher res and a gazzillion levels of AA.
     
  14. wyx087

    wyx087 Homeworld 3 is happening!!

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    Batman AA and Mafia 2 are pretty much the only two game PhysX is worth the effort though. i got the 8800GT mainly for Mafia 2, it was brilliant while it lasted, but after completing the game, the 8800GT just ended up in spare-parts box.
     
  15. ian8415

    ian8415 What's a Dremel?

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    Don't get Physx confused with in game physics, all games have physics software running to bring the game to life, Nvidia are just trying to monopolize it under the Physx branding to make you buy hardware, any one interested in physics google havok
     
  16. Bakes

    Bakes What's a Dremel?

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    Amusingly, PhysX is used in one way or another by a large number of AAA games - most Unreal Engine games for example (which nowadays is a very large number). It's just that most of the games that support it don't use the hardware API. As a brilliant example, there is a PhysX SDK for the Wii.
     
  17. Deders

    Deders Modder

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    Different games work optimally in different ways:

    For Arkham Asylum I got the best performance when I disabled SLI and had one of my 9800gtx+'s dedicated entirely to Physx. I think this is partly to do with Latency issues of switching between physx and graphics calculations, and partly because there was so many physx enabled objects that there weren't enough shader cores left to calulate them efficiently, so you'd have to wait for a single shader to do 2 calculations instead of just one for the scene to update itself.

    From what I've read Fermi GPU's have improved the latency situation and should have more than enough cores to handle the game on one card. Recently I've not even been able to load Arkham without it crashing to the desktop if I have SLI enabled.

    Another thing I noticed was that when running the Physx tests in 3D Mark Vantage was I got slightly higher CPU scores when SLI was disabled.

    I found that Mafia 2 also benefited form having SLI disabled so 1 card was dedicated to Apex/Physx calculations.

    Just cause 2 on the other hand handles its Nvidia only Gpgpu calculations quite well when SLI is enabled but if you look at the GPU usage in GPUz you can see that when 1 card is at 100%, the other is only working at ~80%. this indicates that while both cards are rendering the graphics, only 1 card is doing the Physx Calculations.

    For the most part I think that with 2 480's you should have enough grunt to be able to happily run the graphics of most games on one card, leaving the other to calculate Physx if necessary, the only possible exception could be Metro 2033 if you're running it at very high res. But even then If you find you need SLI for full detail you can run most of the Physx on the CPU.

    Now that DX11 is out, I think Physx will be replaced with a solution that works on both AMD and Nvidia cards without having to have a dedicated card so it would seem superfluous to invest in a 3rd card (and the extra power consumption) that will hardly be used when you can get optimal performance just by enabling/disabling SLI when neccesary.
     
  18. Bakes

    Bakes What's a Dremel?

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    More likely because the GTX+s were spending all their processing slots on the graphics. If you were to set vsync on, it would probably help (as long as your graphics cards on their own could manage 60fps constant).

    Arkham works fine for me, GTX580, 2560x1600, 4xAA, full physx.
     
  19. Deders

    Deders Modder

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    That's pretty much what I meant, that coupled with the physx latency issues of pre-fermi cards means I can't run Arkham and the physx at the same time on 1 card, even with V-Sync enabled. It's why they recommend a dedicated 9800gtx+ for Physx on high in the games settings.
     

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