ATI and physx?

hi,
i posted about this a week ago, but cant locate my post.

I see anymore, physx on certian games..is this something that the 5970 or 5k series has or doesnt it?
I was told the radon does ATi's version of physx but it isnt advertised like nvidia and its built into the chip/ccc..is that true?

thanks
phil
21 answers Last reply
More about physx
  1. Ati can do physics (sp?) just not 'Physx' which is an Nvidia based throw off ( or a perversion some would say). Also, the CPU can do physics as well, though it is debated how much better it is, or can be at doing them.

    Some games come with their own physics like Crysis, or use Havok like BFBC2 which just released for example. They both do a great job without lowering fps much.

    If you see 'Physx' in a game, your best bet is to leave it to 'off' I have noticed that fps will drop by up to 80% in some games with an ATI card trying to run 'Physx'.

    Does this mean your card is not powerful or can't handle such a task ? Certainly not, it is just hardcoded for Nvidia hardware, so performance will often be terrible using an ATI card.

    There seems to be one exception to this rule, which I cannot explain:

    In Metro 2033 which released yesterday, applying 'use advanced physx' in the game options menu only drops fps a little, and by the same amount on BOTH Nvidia and ATI cards. So, technically I am running Nvidia based Physx on my ati card, unless someone can explain the situation further.

    Anyways, hope some of that helps clear some things up.
  2. pnico said:
    hi,
    i posted about this a week ago, but cant locate my post.

    Is this the post you can't find?
    http://www.tomshardware.com/forum/283203-33-answer-nvidias-physx
  3. Annisman said:
    Ati can do physics (sp?) just not 'Physx' which is an Nvidia based throw off ( or a perversion some would say). Also, the CPU can do physics as well, though it is debated how much better it is, or can be at doing them.

    Some games come with their own physics like Crysis, or use Havok like BFBC2 which just released for example. They both do a great job without lowering fps much.

    If you see 'Physx' in a game, your best bet is to leave it to 'off' I have noticed that fps will drop by up to 80% in some games with an ATI card trying to run 'Physx'.

    Does this mean your card is not powerful or can't handle such a task ? Certainly not, it is just hardcoded for Nvidia hardware, so performance will often be terrible using an ATI card.

    There seems to be one exception to this rule, which I cannot explain:

    In Metro 2033 which released yesterday, applying 'use advanced physx' in the game options menu only drops fps a little, and by the same amount on BOTH Nvidia and ATI cards. So, technically I am running Nvidia based Physx on my ati card, unless someone can explain the situation further.

    Anyways, hope some of that helps clear some things up.



    that's great! i use ATI too, can i ask what card do you use?
  4. I use my 5970 with a 9500GT 1GB together having the Nvidia specifically for dedicated Physx processing.

    Works great. I have not done benchmarks with and without the Nvidia card being used for Physx in Metro 2033 I only assumed that it was helping.

    You may not actually be seeing the Physx in Metro 2033? Do you get the smoke clouds that linger after throwing a grenade... seems to be the most immediately noticeable effect.
  5. +1 to Annisman- he's right on the money. I'm impressed though about the Metro 2033 though- how is ATI's hardware running Physx???
  6. Odds are, the physX option in Metro 2033 is either run on CPU for both, or was setup to just not require a lot of computational power, so it runs fine on a CPU.

    I highly doubt the physX option in that game runs on ATi hardware.
  7. I would agree, but if you can turn on PhysX and it doesn't cripple the hardware, thats very interesting.
  8. bystander said:
    Odds are, the physX option in Metro 2033 is either run on CPU for both, or was setup to just not require a lot of computational power, so it runs fine on a CPU.

    I highly doubt the physX option in that game runs on ATi hardware.



    But it does.
  9. Annisman said:
    But it does.


    How do you know it's running on the ATi hardware, and not the CPU?
  10. It might be, but then it wouldn't be 'Physx' anymore now would it ?
  11. Annisman said:
    It might be, but then it wouldn't be 'Physx' anymore now would it ?


    PhysX is an API that does indeed run on the CPU. It always has. It just doesn't perform as fast as when it's run on a physX enabled video card.
  12. Physx runs on the video card, why would Nvidia make a physics api to run on the CPU ?

    what you mean is physx CAN run on the cpu.
  13. The API performs all the same tasks it can on a CPU as it does on a GPU, it just isn't "GPU accellerated". The API is designed to perform faster on Nvidia GPU's than it does on the CPU. Of course, if the dev's choose not to use use it too heavily, the CPU can perform PhysX just fine.
  14. bystander said:
    The API performs all the same tasks it can on a CPU as it does on a GPU, it just isn't "GPU accellerated". The API is designed to perform faster on Nvidia GPU's than it does on the CPU. Of course, if the dev's choose not to use use it too heavily, the CPU can perform PhysX just fine.


    No, the CPU can perform 'physics' just fine (ala Havok) but it rarely handles 'Physx' well.

    darn Nvidia and their naming schemes!
  15. Annisman said:
    No, the CPU can perform 'physics' just fine (ala Havok) but it rarely handles 'Physx' well.

    darn Nvidia and their naming schemes!


    Yes, that is the suprising part. That's all I'm saying, the CPU seems to be able to handle the physX. It could also be they enabled multiple cores with PhysX, which is rarely done, or maybe they just didn't use a lot of physX calculations.

    The point is, ATi cards currently do not run physX, so that means the game runs physX on the CPU well enough to have high performance. This would also explain why it runs better in ATi cards than Nvidia cards. Instead of slowing down the video card with physX and rendering, the ATi systems get to have their cards focused on rendering, and the CPU seems to be plenty of power for the amount of physX used.
  16. Oh, I see what you are saying, that makes some sense.

    I should point out that some Nvidia users with dedicated physx cards are only noticing 10-15% usage on their physx cards (generally 50-60% is usual in Physx enabled games) So maybe the 'Physx' in this game are half-baked and don't require a gtx 285 to run lol.
  17. That would definately indicate that is the result. It's a pretty good move too, that way everyone can play it the way it was meant to be played :)
  18. I don't know, something tells me Nvidia would rather have it unplayable on ATI setups like their other physx titles seem to be. (The physx part that is, not the actual game by itself)
  19. Interesting guys! You learn new things all the time:-)

    Annisman- I agree about the fact that Nvidia would probably prefer it if ATI setups would be unable to play the PhysX part of the game successfully- thats one of the things they push. Thats one reason I like that ATI is pushing the open standards that will improve gameplay and visuals for ALL PC's regardless of what hardware they are running.
  20. Definately one of the reasons I dislike Nvidia as a company, however their products I will still use of course, if they are the best performing.
  21. Agreed- I'll use whatever is the best in my budget from whichever company, even if I don't love the way the company plays the game:-) Thats why I have an Intel CPU even though I like the way AMD runs things better.
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