I did a lot of research on Physx a couple of years ago. And I mean, an awful, awful lot. From running it on a standalone card, to running it on a second card, using the actual Ageia PPU 128mb, using it with Crossfire (using GenL's hybrid Physx mod) and so on. I deduced that if you have a faster card (say a GTX 480) and you use something slower than the master card in gaming terms (ignoring Physx) then the results will drop. The only reason I could think of in the end was that the Physx PPU is somehow integrated into the card and uses its clock speed. Thus, something like a GTX 480 was a faster ,higher clocked card than a 8800 Ultra and thus it was not worth using the standalone card. Back then (when the game at hand was Batman AA) I realised that you needed at least a GTX 460 as the stand alone card to stop your game grinding to a halt. Which is why when the OP said a card like the GT 640 I said no chance. I didn't have the time to reply in depth as to why back then. At the time of my testing I also bought a used GT 240 and tried that and again, it really hurt the performance. Basic low end cards may physically support Physx but they're useless at it.
You need to stay with the same architexture to lose performance if you buy a 6/7 series gpu you need a 6/7 series physics card if thats what your trying to do. AMD card with nvidia physics card will always be a reduce in performance for the record.
I actually did really well with my 5770CF (runt and dropped frames and all ) and a GTX 460. Argh stop this nonsense, now I'm thinking what card I can add to my 7990 to give me Phsyx
Oh no you don't... As said, the fps were/are improved with my 460 when pairing it with both a 580 & a titan. & i've no idea what you're on about with an AMD card? - On the games that allow it, you're suggesting that it will be slower to run PhysX on a (decent) dedicated gpu than on the cpu? This is just nonsense - though with the proviso that the PhysX card needs to be up to the job compared to the main card (& obviously more powerful than the cpu in doing the calcs). - if, however, you're suggesting that it could be slower to run PhysX with an AMD + NVidia card than not run it at all, then quite possibly - but this would be the same as ramping up any major graphics setting in a game from being off/it's lowest setting to being on/maxed out... (do you personally play all of your games at 640x480, no AA, lowest texture settings, lowest DoF, PhysX disabled, etc, etc so that there's max fps - or do you choose settings that are appropriate to your gfx card(s) to get decent res/effects whilst maintaining a decent fps?) ...so, yet again, with PhysX (as with any other setting) you need to buy a card that's up to the task.
I personally play all my games on 2 680s in sli at 1080p so pretty overkill for the setup. Very few physics games that are actually good though, Mafia 2 is probably the best example of physics working.
I should find the link but in Mafia 2 , a Russian website reviewd it with various PhysX cards - and for that title a GTX 260 was ideal (with a GTX 580 main card) with PhysX to max. I have an aegia PhysX card , and performance wise , a GT630 is faster at PhysX.
it wasn't a serious suggestion that you would be gaming at 640x480, etc... The point was that as you increase the res & increase the snazzy settings on a potentially demanding game then the fps will lower. Now, with a good enough NVidia setup for the res then you can naturally enable PhysX & it'll be perfectly playable, but it will still lower the fps by enabling it. So, with an (decent) AMD + (half decent) NVidia setup - which is obviously far faster than trying to use PhysX on the cpu - then similarly enabling PhysX will lower the fps, but it doesn't make it magically unplayable. As to whether buying a card for PhysX is worth the money for any particular game, that's a completely different call based on personal choice for aesthetics... (it has nothing to do with whether a card is powerful enough to do so, which is what the OP was after knowing, or your mistaken statements that cards have to be of the same architecture or whatever) ...but arguably as you 'could' play most games at 800x600 (640x480 was probably an over exaggeration) & there's no *need* to enable AA & whatnot, spending money on anything that's more powerful than is needed for that is also simply personal choice for aesthetics. Clearly it will depend on res & other settings, but my belief is that the jump from a 260 to a 280 made a significant difference to the r.l. playability with Mafia2 (paired with a 580); even at some sub-1080p settings. &, quite obviously, Mafia 2's not exactly the latest game - though naturally you were referring to that d.t. rollo's comment. Now, the 280 isn't that far off the performance of the 192 bit versions of the 460 (albeit notably slower than the 256 bit ones) so it's not as though it's looking at completely different levels of min GPU performance for a PhysX card. Well, there's always a degree of overlap between one range of models & the next - esp when you start including dual gpu cards. All of that said, i'm certainly not suggesting that anyone should actively buy a 280 over a 460 (particularly a 256-bit one) as they are slower, run hotter & use more power.
