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Old 11-20-2008, 07:54 PM
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Nvidia dedicated PhysX with mixed GPUs
Nvidia's newest drivers add support for mixed graphic cards in order to run one as a dedicated PhysX card. While the previous drivers allowed you to run dedicated PhysX on a single card if you had matching cards, the new drivers allow for mixed cards. "How/Why is this a big deal?" You ask. Well, what this means is you can have one card, say you have an 8800 GT, and then you upgrade to a new card, say a 9800 GT. Now, instead of selling the old 8800 GT you can now use both (provided you have an SLI capable motherboard and power supply powerful enough to run both) and set the 8800 GT to be a dedicated PhysX card. You would then get the full power of the 9800 GT running just graphics and the full power of the 8800 GT running PhysX. Previously you'd be running both on the 9800 GT, theoretically losing at least some power on one application as its power is being split.

Right now there are only about 6 games on the planet that benefit from PhysX hardware acceleration, so I'm certainly not going to tell you to run right out and do something like buy an 8500 GT or 9500 GT just to run dedicated PhysX, but that is an option now. Is it necessary? Does PhysX reduce your overall framerates enough when running both graphics and PhysX on a single card to be of concern? That I can't say yet. I'm sure over the next few days and weeks we'll see reviewers asking exactly that question. I'm sure we'll also see comparisons like a single GTX 260 running both compared to something like a much lower cost option like a 9800 GT running graphics and a 9500 GT running PhysX.

There are, however, limitations. PhysX will only run on series 8 cards and higher (8xxx, 9xxx and 2xx), you will need an SLI capable motherboard, and you will need a power supply strong enough to run both cards. But this could be very exciting news as time goes on as it provides a very low cost means of users having a very powerful physics accelerator making the prospect of PhysX much more attractive to game developers as they know more people would have access to it.

At the time of this writing I'll predict that cards in the $40-75 range (new) will have more than enough power to run current PhysX acceleration. These would be; 8500 GT, 8600 GT, 9500 GT, 9600 GT. I'm betting more powerful cards would be better sold on the secondary market to recover money when you upgrade and keeping dedicated PhysX on one of these lesser cards. (It would be great if you could find one with a passive cooling system as well so it doesn't add any noise to the system. Something like this XFX 8500 GT may be an ideal choice for this.) Again, is buying an extra card a better choice than spending the money on a slightly better single card than you'd otherwise get to run both? Only time and reviews will answer that question.
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Old 12-02-2008, 08:49 AM
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Running an old card for PhysX is great but UT3 is the only top game I know that supports it that I would play and even then is only the newer multiplayer maps. Tho one hte plus side I've been hearing that with it enabled you get a good 30fps boost during heavy fighting sections. So until more physX games are released is it worth it? Does anyone have any ideas about upcomming games that will support it?
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Old 12-02-2008, 02:46 PM
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I don't know about upcoming games, but here is a list I found of some games that support PhysX.

http://www.nzone.com/object/nzone_physxgames_home.html
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Old 12-05-2008, 05:39 PM
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Do NOT trust that list.

There is some confusion being used there at that site, and on the old Ageia site, and I'm sadened to see that Nvidia continues the confusion. Yes, that site is correct in that those games are all PhysX accelerated. No, the decptive part is that those are not all hardware accelerated.

There are two bits to the equasion...
- PhysX software that runs the physics calculations
- PhysX hardware that accelerates those calculations

The software is simply a tool that Ageia designed for physics calculations that developers could plug into their games to run physics. (So said developer doesn't have to go throgh the trouble of making a proprietary physics package.) It does accelerate physics calculations, but it does not automatically send those calculations to the PhysX hardware card. This was a huge factor that prevented adoption, as those of us 'in the know' knew that the card was not a magic solution that worked in all cases. The vast majority of users never knew this, and still don't, and that fact is hidden so the public perception remains that it will work in all cases.

One example I used in another thread where we went around and around on this is that it's like Math. There is Math and then there is Math and using a Calculator. Just because something is math doesn't mean that you are using a calculator. If a professor says 'we have a math test today' that doesn't mean the same thing as 'we have a math test today and you can use a calculator'. With the vast majority of tests that calculator is sitting in your bag doing absolutely nothing while you use math.

The game in question must be coded to offload the PhysX code calls onto the PhysX accelerator in order to have hardware based acceleration. If those aren't in place it will run in software mode only. There are only 9 games total (some don't really count as they are like Cell Factor and not a real game) that feature hardware based acceleration. And the majority of them are like UT3, where it's only used in a few levels, or used very sparingly.

Sadly when Nvidia absorbed Ageia the page which made it a little more clear was removed.

Now... if that's changed since the Nvidia buyout, if that page is correct in that they altered it to work automatically, that would be completely new and unnanounced information. Note though that said cards must be CUDA compatible, which the Wii, 360 and PS3 are not, so those are automatically disqualified for sure. The only cards capable are the series 8 and forward. But, to my knowledge, this has not changed and the game must be specifically coded and there are only 9 coded to do hardware based acceleration.

If you look at the BFG PhysX card page and click the titles tab, you'll note it only references 9 games. (I'm pretty sure that Bet on Soldier thing are expansions.) I'd think if the Nvidia PhysX buyout changed this, it would also affect the original PhysX card and BFG would not be referencing the same number as before.
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Old 12-05-2008, 05:49 PM
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Quote:
Originally Posted by Javaman View Post
So until more physX games are released is it worth it? Does anyone have any ideas about upcomming games that will support it?
The question goes much deeper than this. The question also needing to be asked is - should I get a single more powerful card, or run a dedicated PhysX card along side a dedicated graphics card?

Consider the following:
Evga GTX 260 core 216 $260
vs.
Evga 9800 GT $115 and Evga 9500 GT $60, $175 total

Notice that the GTX 260 is much more expensive compared to the combo 9800 GT / 9500 GT. But the question must be asked is; is the GTX 260 running graphics and PhysX going to perform better (at say 1680x1050 at high settings) compared to the 9800 GT running dedicated graphics along side the 9500 GT running dedicated PhysX.

Things like this haven't been answered by reviewers yet, so we don't even know if it's worth it to consider dedicated PhysX on a second card at all compared to simply getting a single more powerful card and running both.

With the current minimal impact that PhysX has had so far running on graphic cards, it's possible it may be years before we need to consider a dedicated card at all as opposed to simply having a better single card running both which is a current generation card.
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