What happens with edit processing using multiple video cards?

I use three monitors for editing. With Photoshop, I will commonly have the edit screen filling my IPS calibrated monitor plugged into my fast, 2gb video card; the menus and tools on a secondary (cheaper) monitor connected to a 2gb card; and another monitor available for any other purpose connected to that same 2gb card. Both cards are CUDA capable.

When editing on Premiere Pro, CUDA is available for the Mercury playback engine for either card. But of course, I'd want to make sure it's my primary card that bears the weight of the gpu processing. How do I know that's what's happening?

Can I presume if I've got the timeline and preview windows on the screen connected to the primary card that all the processing is being directed to that card? Or did Premiere Pro pick up one card or the other (perhaps depending on the PCI-E card slot) as it started and does all its processing on that card regardless of the monitor location of application elements?

For Premiere, Adobe's engine is using OpenGL. A graphics card that has CUDA support is basically giving it's processors to OpenGL and can help with raytrace effects or speed up render times then if it was with CPU alone. This is irrespective of what a card is displaying on which screen. If you have several graphics cards, then they're all going to be utilized by the OpenGL engine (OpenGL will use them whenever there's more processing demands). With todays world of multiple processors, cores, and GPUs, it appears that software developers are trying to elminate customization with performance settings. I've found that if I do try adjusting the performance settings in Premiere, my renders can crash: I just keep things on auto. If you do want to tinker, then you could try OpenGL settings in the Nvidia control panel. In Maya, I can have real performance boosts if I do manually enter the number of threads it can render with (by default, it must not utilize all the threads of my computer).

So are you saying I could enhance performance by packing all my video slots with high performance cards? Premiere would see and utilize any card in the system as needed?

Theoritically you could....but Nvidia markets their high end cards with having more cores (IE better to have one expensive card vs multiple lower end cards). Their professional Quadro line also has better support for OpenGL and stated CUDA cores. What kind of performance you get with multiple video cards vs CPUs is a bit of a crap shoot (depends on the software and what features are utilized). Personally, when I'm upgrading workstations, I look at getting the most CPU cores first. Dual Xeons that are 6 or 8 cores. I think the really expensive video cards are better geared for 3D tasks: if you have a large scene that has a lot of polygons or texturemaps. A $4000 card is overkill for video editing...

http://www.nvidia.com …/quadro-desktop-gpus.html

davesrose wrote in post #17510633
Theoritically you could....but Nvidia markets their high end cards with having more cores (IE better to have one expensive card vs multiple lower end cards). Their professional Quadro line also has better support for OpenGL and stated CUDA cores. What kind of performance you get with multiple video cards vs CPUs is a bit of a crap shoot (depends on the software and what features are utilized). Personally, when I'm upgrading workstations, I look at getting the most CPU cores first. Dual Xeons that are 6 or 8 cores. I think the really expensive video cards are better geared for 3D tasks: if you have a large scene that has a lot of polygons or texturemaps. A $4000 card is overkill for video editing...

http://www.nvidia.com …/quadro-desktop-gpus.html

How would Scalable Link Interface (SLI) work into that? Is that a technology that each application must be designed to use?

Added: Just did some Googling and discovered that Premiere Pro doesn't get along with SLI.

Think SLI was more a marketing thing for gaming. With high end graphics, it's all about OpenGL compliance and multithreading (and why Nvidia has a pricing premium with Quadro cards and CUDA vs GeForce).