mixing graphic cards Resolve

Do you know if it works to mix one:
Nvidia GTX 570 for Apple Mac Pro 2.5 GB
and
Two: NVIDIA GeForce GTX 580+ 3072 MB GGDR5 SDRAM?

Will I get more realtime in Davinci Resolve 9 with the above setup than if I go with three Nvidia GTX 570?

SETUP:
Mac Pro Two 2,4 GHz 6-Core (12 core) 28 GB RAM
PCI 570  Image Processing and GUI with 2 screens connected.  
CUBIX with 2 additional cards.

Best Martin
Colorist
http://www.fabiofilms.com/

[Peter Chamberlain]

Hi Martin. With the exception of a single shared GPU configuration, when you connect a GUI monitor. or two, to a GPU it will be used for image processing. In this case the other GPUs are used. It's common to have a lower performance GPU for the UI and one or more for processing GPUs and the GTX580 is a good choice.
Peter

Thanks for the answer! I already bought the GTX 570 so that will unfortunately be use for GUI then, to bad And I will get 2 GTX 580 to put in a Cubix. Can I buy 3 GTX 580 cards and use the GTX 570 for GUI? Or does the 3 graphic card limit stop the last card from being used on a Mac Pro?
Best Martin

[Peter Chamberlain]

Hi Martin, please refer to the config guide. Mac OS X permits four GPUs, so one UI and three for image processing. The GTX570 is overkill for the UI but may be valuable if you have other applications that can't effectively use image processing GPUs and must use the UI GPU.
Peter

We mix cards and it works fine. We have one 580 classified, one 680 and one 690 in the system at the moment.

It would be REALLY Nice with an option in resolve for it to not dedicate one GPU for GUI. Don't see the reason or benefit for it since it works fine with something like one 570, 580 etc. Would it be possible to add an option like that?

[Peter Chamberlain]

Hi Neo, mixing image processing GPUs is generally ok, assuming the same driver worked for all, but the will run at the rate of the slowest card. In your case, the 690 runs similar to two 670s. While we do support a single GPU config, as authors of the software, trust us, it's better to have a separate image processing GPU as per the config guide. We use it for a lot more than just the UI screen.
Peter

Hi Peter

Oh, that is interesting. I didn't know that the slowest card sets the speed limit. Are we purely talking about the MHz? Is that a OSX or Resolve thingy?

So are there any whitepaper on what the GUI-gpu is used for or so? I like stuffs like this and really want to dig my teeth into it to get a better understanding. When doing tests, maybe not the most scientifically tests, the GUI-GPU doesn't seem to be that important. I have a spreadsheet with my tests over here: https://docs.google.com/spreadsheet/ccc ... TZnc#gid=0

When I look at that it feels that in a real life scenario the user would gain more from being able to have the GPU GUI used for video processing too. I know that I don't see the whole picture so I know that I'm on thin ice and maybe in over my head. =)

But for instance compare the numbers for this setup:
Video card 1: GeForce GTX 580 - GUI Only
Video card 2: GeForce GTX 690
Video card 3: GeForce GTX 690
Video card 4: GeForce GTX 680

With the numbers for this setup where there's an ATI card in the MacPro:
Video card 1: GeForce GTX 580
Video card 2: GeForce GTX 690
Video card 3: GeForce GTX 690

The later setup gives pretty much identical results in Resolve but if the 580 in the first setup could be used for more than GUI I'm certain that it would see a pretty big boost in benchmarking. Also, why isn't the ATI reported as a GUI only GPU? When running a system with only an ATI it is reported in the lists as "Video card 1: ATI Radeon HD 5770".

I admit I might be a bit snowed in on numbers but that's what testing and tweaking does to ya.

Cheers

[Peter Chamberlain]

Hi Neo, we don't publish the details but to give you an example; the on screen cursor, windows etc, are interactive on the UI and also show on the SDI out so you can see them on the grading screen. These are done in the UI GPU after the images are processed.

The speed tests you are performing are comparing image processing speeds between GPUs and I doubt these tests are influenced by the UI GPU. Image processing GPU speeds are more then just MHz. We also consider number of cores, internal ram, shared vs non shared ram, its speed, etc etc.

Sorry I cant give you more technical detail but ultimately a GTX470 or the Q4000 is a better choice than a GT120... but the 120 will work.
Peter

The speed tests you are performing are comparing image processing speeds between GPUs and I doubt these tests are influenced by the UI GPU. Image processing GPU speeds are more then just MHz. We also consider number of cores, internal ram, shared vs non shared ram, its speed, etc etc.Peter

They are influenced in the way that if one GPU is dedicated and locked to the GUI I have one GPU less for image processing speed.