Originally Posted by TheSurroundGamr
That's fine and all, however, you have to remember that I'm using three GPUs to power three monitors. And that's why I've asked this question. I've actually seen a lot of data on a single GPU + deciated PhysX card. I was wondering about 3 GPUs powering 3 screens. But, thanks!
How does PhysX work with SLI and multi-GPU configurations?
When two, three, or four matched GPUs are working in SLI, PhysX runs on one GPU, while graphics rendering runs on all GPUs. The NVIDIA drivers optimize the available resources across all GPUs to balance PhysX computation and graphics rendering. Therefore users can expect much higher frame rates and a better overall experience with SLI.
(italicized for emphasis)
so that tells me though one card on the SLI configuration is selected for physX the driver distributes the load among all the gpus. btw, through researching for this but never using SLI it was highly recommended to NOT select either card as "dedicated" for physX in the NV control panel.
through some googling there are many threads discussing a single card with a dedicated physX card and a few SLI w/physX card. i'll reference a few threads and sorry my citations are not organized:680 + physx bench
(also benches 680 sli with gt450 physX)GTX 680 dedicated PhysX or SLI?
but specifically this post
I use a 216sp gtx 260 for physx with 2 680's... granted, 90% of my games are non-physx titles, the ones that do use physx, like Batman: AC actually does benefit from using the dedicated phsyx card. Running Batman: AC's built-in benchmark tool, I saw higher min framerate and about 10 fps more average frames. For me I opted to have cool physx effects + a dedicated physx because with the settings including AA and AF maxed out @ 2560 x 1440, the difference between 60 and 70 fps with a higher minimum framerate drop is crucial.
there was also a thread on the nvidia forums but sorry, ATM my eyes are pretty tired and my browser history is rather full to find it. but i will tell you what i will infer with the info i gleaned from reading:
the requirements of using a physX card or not with a/any SLI setup is similar to a single card setup though a bit more complicated:
since the nvidia driver distributes the physX load among the SLI configuration then you need to consider the total core count of all cards and also physX games vary in the amount of cuda cores used for physX . so to break it down in your case; you will have (1344*3) 4032 cuda core with a gtx 670tri SLI and assuming you will be using one of you old gtx 480s for physX that would be 480 cores or just under 12% of your SLI setup. so if you are playing metro 2033 which will use 10% of the available cuda cores for physX then you will have a slight benefit.
but if you are playing batman AC which can use up to ~20% of the available cuda cores then you will see a decrease in performance. i'll have to admit i did pull those physX usage %s out of the air but i think i am close.
edit: ah, and also considering you are looking to run a 2D surround setup - it may even have more of an impact because that would need for physX calculations for the higher resolution. (wow i am tired, i have been staring at your avatar and trancing out for a minute . .
)Edited by looniam - 3/29/13 at 4:49am