I just purchased an MSI GTX 560 ti Hawk (Twin Frozr III) and I was thinking about running Physx on a dedicated card. Clearly, the 560 Ti will be much more than adequate to render any game at max settings and do Physx calculation on top of that, but I was considering that I could potentially increase the lifespan, or possibly overclockability of the card (if I ever do dual monitors) by offloading Physx calculations on a cheaper card.
I did some research and it seems that most people who do this run Phsyx on a card of comparable power to the graphics rendering card.
My question is what the threshold is for avoiding slowdown. Clearly, I need the secondary card to do the calculations at least as fast as the 560 Ti could do both if it were a single card.
What I do not know is what this threshold is. I have a 9600 GSO in another computer that runs games pretty decently for its price, and obviously Physx calculations aren't as taxing as graphics rendering, but I would wager that pairing the 9600 GSO with the 560 Ti would result in a slowdown.
I do not want to spend a considerable amount of money on this plan, and it only really interests me as a hobbyist, but if I could get a card for sub 50 dollars that could do the Physx calcs then I would probably go for that. I know the 9600 GT is considerably more powerful than the GSO, and they sell for pretty low prices. Would a card like that suit my purposes? Or am I going to need something more like a GTX 260 or something? Or perhaps somewhere in between like an 8800 or 9800?
The 560 Ti is far from maxing any of the latest games. Even two of them won't get you a consistent 60fps on, say, Crysis 2 DX11 with all the goodies on.
I think just about any recent low-end Nvidia card would do it, but I don't know about the 9600. A GTX 440 or 250 would be fine. They'd handle the processing well enough; the idea is to take the load off the 560 Ti.
Personally, I think you'd be better off putting away the money toward another 560 Ti in the future. SLI will give you a far, far greater benefit, even dollar for dollar, than a dedicated Physx card.
First of all, there are very few games which support GPU accelerated PhysX, the rest depend on CPU Physx power. How much power you need for a dedicated PhysX card depends on the game.
As you see GTX 260 and above do a good job in Physx based games, anything below wouldn't provide you with that fancy Physx details but at least your performance will not be throttled if you turn Physx on.
If you don't have a game that supports GPU accelerated PhysX, then you're just providing power to a graphics card in your case.
Which GPU accelerated PhysX games do you play? That is the first question you need to ask.
Then, that chart from ilysami is a good for gauging how much card you need. A 260 or above should be considered the minimum. The key is the number of CUDA cores, which should be about 188 at minimum (GTX 260 or GTS 450 or GTX 550 Ti and above).
Well I have Crysis and Crysis 2 and a couple of other hard copies of games and then like 100 steam games, so I'm pretty sure that at least some of the time I'll be benefitting from Physx, at least enough to make the offload worth it, but if you really don't think that I can run anything less than a GTX 260 then I don't think its worth the money. I mentioned that card because it is getting replaced by the 560 ti but I am moving it to a machine in my office, so I can't pair it with my 560, which means I'd have o buy another card, and I can't afford another 260. I noticed the 9600 GT is in faction that chart and I have a friend at who uses the setup I mentioned with a 9600 GT and he seems to get good performance. Can that card suffice do you think? Why do you bring up 188 as the preferred core count?
The cores are what determines the PhysX processing power. You will gain a benefit from the 9600GT, just not as much as a 260. It will show a performance increase. Try it out, there's nothing to lose.
Be aware that we are only talking: Unreal Tournament 3, Batman: Arkham, Metro 2033, Mafia 2, and those listed with GPU acceleration on this page (there are some due to be released in 2012): http://en.wikipedia.org/wiki/PhysX
You should test it, with and without the dedicated card... some times you can lose performance! Truth is, the dedicated card can't be much slower then main card, or you better just run a single card, or go for sli! So... unless you get a 550 or something like that, you better invest money in sli... dedicated physx is for high-end rigs... sry!