Physx

petapacket · 14 Jan 2013 at 13:34

Is it correct that it's supported on a game basis, by the development team as integral code and then executed client/gamer end. Does this mean it's possible to enable Physx on AMD GPGPU?

Gregster · 14 Jan 2013 at 13:37

PhysX can be run on the CPU with AMD GPU's but requires a hack to do this.

Solaris · 14 Jan 2013 at 13:37

It is code built right into the game engine that runs on the Nvidia GPU.

You could probably run it on AMD GPU if you included the Physx API in the AMD driver, but it's all proprietary closed-source code that the community will never get its hands on.

So no...

Solaris · 14 Jan 2013 at 13:39

The hack runs the Physx calcs on the CPU, not the AMD GPGPU. Or AMD cards running graphics with a slave Nvidia board doing physx calcs.

http://www.tomshardware.co.uk/nvidia-physx-hack-amd-radeon,review-32051.html

shankly1985 · 14 Jan 2013 at 13:41

They is only a handful of games that use it 21 games I think. Still only One game gets it done correct "Borderlands 2"
So has it stands right now I wouldn't worry about PhysX, Unless they is a game you really want to play that uses it and you are willing to pay the extra price tag for it.

petapacket · 14 Jan 2013 at 13:49

gregster said:
PhysX can be run on the CPU with AMD GPU's but requires a hack to do this.

Thought so.

When Physx is used properly it can look amazing, let alone the potential for changing the gameplay by making objects relate to reality closer. Thing is, Nvidia's cards at current can produce more advanced graphics than AMD's cards due to the Physx technology, questions is; £200 additional charge worth the increment for today's games?

Gregster · 14 Jan 2013 at 13:56

petapacket said:
Thought so.

When Physx is used properly it can look amazing, let alone the potential for changing the gameplay by making objects relate to reality closer. Thing is, Nvidia's cards at current can produce more advanced graphics than AMD's cards due to the Physx technology, questions is; £200 additional charge worth the increment for today's games?

How come £200 additional charge?

ALXAndy · 14 Jan 2013 at 14:11

Hmm.

Physx can be ran on the CPU (or at least I thought at last time of checking) without a hack. Simply turn it on in the game and it will fall onto your CPU and mangle it making the game crawl.

You can run a secondary Nvidia GPU and hack that to run Physx using GenL's Physx mod. It works very well. All you have to do is install the Nvidia drivers then run the hack and it automatically enables Physx on the secondary GPU.

petapacket · 14 Jan 2013 at 14:15

The additional charge is me choosing between a 7950 and a 6804GB. I could save £200, by purchasing the Radeon and enabling Physx with my current 570. Does anyone know how the physx calculations are piped from one card to the other and implemented well.

ALXAndy · 14 Jan 2013 at 14:28

petapacket said:
The additional charge is me choosing between a 7950 and a 6804GB. I could save £200, by purchasing the Radeon and enabling Physx with my current 570. Does anyone know how the physx calculations are piped from one card to the other and implemented well.

Basically Physx used to run on a stand alone card (called a PPU, Physx processing unit). It had 128mb ram and was made by Ageia, the people who invented Physx..

Unfortunately for them AMD and Intel (yes you read that right lol) were working on something called Havok. AMD and Intel both realised that Havok could be ran very well just on a CPU so probably wasn't worth wasting money on trying to monopolise it as people simply wouldn't buy into it. Snake oil products they are known as.

Any way, Nvidia (who like to spend loads of their earnings on monopoly based rubbish) bought out Ageia and incorporated the Physx PPU into the GPU core (simply bolted it on).

Thus, when you run Physx on an Nvidia card it uses the built in PPU that does actually exist. Thus, when you run an AMD card and use a Nvidia card for Physx it works exactly the same way.

After extensive testing with the PPU mods and etc I can offer you the following advice...

1. Physx PPU calculation speeds are affected by the clock speed of the GPU and the CUDA cores (though I am not quite sure why.. Clock speed I get, CUDA shouldn't affect it but it seems to ?!?!?)

2. Running a second card (if you have a AMD as the master card) works very well, however, you are doubling your power consumption and then you have the other multiple GPU annoyances like heat and closeness of the cards ETC).

In summation if you are really into Physx and see it as important then just buy a Nvidia GPU in the first place. Running more than one card is not really economical enough just for Physx. It's over rated (and nothing Havok can't do, please see Just Cause 2 for an example, or even Fallout 3) and basically a waste of money on Nvidia's part (much like 3Dvision ETC ETC only a very small minority will be brain washed enough to choose a Nvidia GPU for 3D or Physx.

Nvidia love buying into gimmicks and then charging us for the pleasure even if we think they are stupid and don't want or need them. This is why they got Kepler so right as they concentrated more on a budget than just bolting on tons of needless crap that can't be used for gaming, yet, in the case of Fermi just makes the heat and energy usages rocket without providing anything in terms of performance for gaming.

Gregster · 14 Jan 2013 at 14:29

petapacket said:
The additional charge is me choosing between a 7950 and a 6804GB. I could save £200, by purchasing the Radeon and enabling Physx with my current 570. Does anyone know how the physx calculations are piped from one card to the other and implemented well.

Bad analogy.

That is like me saying, I want to get a 7970 but I see I can get the 660TI for £200 less.

You can do Hybrid but I have no clue how you go about it.

ALXAndy · 14 Jan 2013 at 14:32

gregster said:
Bad analogy.

That is like me saying, I want to get a 7970 but I see I can get the 660TI for £200 less.

You can do Hybrid but I have no clue how you go about it.

1. Run driver sweeper make sure there are no VGA drivers on your machine at all.

2. Install ATI/AMD GPU. Install the drivers.

3. Install Nvidia GPU install the drivers*

*make sure they are supported by GenL.

4. Double click GenL's Physx mod.

Done.

petapacket · 14 Jan 2013 at 14:38

gregster said:
Bad analogy.

That is like me saying, I want to get a 7970 but I see I can get the 660TI for £200 less.

You can do Hybrid but I have no clue how you go about it.

It's not an analogy insofar as the bounds haven't been described to you, 7950 has comparable FPS rates for popular titles as 680, but lacks physx. I already own a GTX570, i could load Physx from those CUDA and do the rendering on the Radeon. Makes sense in this context and is not parallel to what you said.

ALXAndy, are all CUDA used for Phsyx with this 'hack', if that is technically possible?

ALXAndy · 14 Jan 2013 at 14:48

petapacket said:
It's not an analogy insofar as the bounds haven't been described to you, 7950 has comparable FPS rates for popular titles as 680, but lacks physx. I already own a GTX570, i could load Physx from those CUDA and do the rendering on the Radeon. Makes sense in this context and is not parallel to what you said.

ALXAndy, are all CUDA used for Phsyx with this 'hack', if that is technically possible?

I'm not sure if the CUDA is being used no. I do know that the PPU is somewhere on the Nvidia die and that it is affected by clock speed and the overall spec (and CUDA cores) of the card.

haha just found this pic. Two 3870x2 running in Quadfire and a 8800 Ultra for Physx using GenL's mod. Two power supplies were needed and a really big desk fan to suck air in from the window. I think I lasted about an hour before I started to drip sweat and get spots and called it a day.

petapacket · 14 Jan 2013 at 15:06

Heh, sounds horrible. I bought an aircon unit to make gaming in summer tolerable, i can turn my room into an icebox.

spoffle · 14 Jan 2013 at 15:55

petapacket said:
Thought so.

When Physx is used properly it can look amazing, let alone the potential for changing the gameplay by making objects relate to reality closer. Thing is, Nvidia's cards at current can produce more advanced graphics than AMD's cards due to the Physx technology, questions is; £200 additional charge worth the increment for today's games?

PhysX will never be used to change gameplay, so to buy on potential isn't a good idea.

A games developer will never implement PhysX that changes gameplay because you would NEED an nVidia GPU to then play the game, meaning all those people that don't have nVidia GPUs wouldn't be able to play the game, no developer is going to limit their potential customer base to such extent.

PhysX will never be "ported" to run on an AMD GPU officially either because it's proprietary technology, nVidia want it all for themselves so that they can use it to attempt to show people how much better nVidia cards are.

PhysX is made to run badly on CPUs on purpose for the above reason, when running on the GPU is an option, so that it makes nVidia GPUs look so much faster than CPUs at processing PhysX.

Games that use GPU PhysX often have the basic physics effects removed to exaggerate the difference that PhysX makes.

Games that actually do use GPU PhysX aren't very common, and a lot of people confuse games that use the PhysX API with GPU PhysX. Out of all the games that actually use the PhysX API, less than 10% actually run on the GPU.

Generally speaking, PhysX isn't really worth investing much money in to, it's a dead technology, it's got a VERY limited lifespan and will be thrown to the side by everyone the moment a non-proprietary hardware physics API comes out, however long that will be.

But in the mean time, actual good physics effects do not need a GPU to run, you just need to take a look at the frostbite engine to see. BF3 and Bad Company 2 both use the Frostbite engine, and have quite advanced physics effects that can run on any hardware as long as it's fast enough.

Yaayuh! · 14 Jan 2013 at 16:28

Borderlands 2 is a good example of how it can run on CPU with an AMD card, badly. You can take such an FPS hit with it.
But it's good to see games are being developed to run it on the CPU if using an AMD card, "Hybrid-PhysX" as such.

Check this out: http://physxinfo.com/news/9425/borderlands-2-is-cpu-capable-of-handling-the-physx-effects/

spoffle · 14 Jan 2013 at 16:33

Rossi~ said:
Borderlands 2 is a good example of how it can run on CPU with an AMD card, badly. You can take such an FPS hit with it.
But it's good to see games are being developed to run it on the CPU if using an AMD card.

Well, it depends, it seems that it doesn't work constantly out of the box for anyone with an AMD card.

When I first got it, I had the option to change the PhysX settings, when I got a 7950, they were no long able to be changed.

Yaayuh! · 14 Jan 2013 at 16:36

spoffle said:
Well, it depends, it seems that it doesn't work constantly out of the box for anyone with an AMD card.

When I first got it, I had the option to change the PhysX settings, when I got a 7950, they were no long able to be changed.

That's strange.
Not seen that before. The game is designed to be able to offload the PhysX to the CPU if not available on GPU.

Running a 7970 here and always had the option. Though can be unplayable on high, have to leave it on low. To make sure the FPS stay above 40~ when things start getting crazy and exploding.
Would also add that with the PhysX on there does seem to be some sort of stuttering occurring as well. Needs to be refined definitely.

spoffle · 14 Jan 2013 at 16:45

It doesn't seem to be consistent as to whether or that happens. There is a work around to get it available at all times though in the form of an ini tweak.

There's rumours going around that PhysX is getting refined to run properly (ungimped) on CPUs anyway.