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

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?

+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???

I would agree, but if you can turn on PhysX and it doesn't cripple the hardware, thats very interesting.

How do you know it's running on the ATi hardware, and not the CPU?

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.

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.

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.

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

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.

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.