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Running two video cards in OS X - Advantages?

U

urchinboy

macrumors member
Original poster
Feb 8, 2008
31
0
I have the option to get a free ATi 3870 video card in addition to my 8800gt. Primarily I work in FCP, Motion, Color and Photoshop. My instinct is to have the 3870 running both my 23" ACDs (one of which is fed through a Matrox MXO. Would there be any advantage in adding the 8800gt back into the system and running one display from each card? So the 3870 running display 1 and the 8800 running through the MXO to display 2.

Would I be likely to see any improvement in things like Motion playback?

Or is it just a really stupid idea on a wet Monday afternoon in London cos I'm a bit bored?

All thoughts appreciated as always...
 
I was under the strong impression you can only load a single set of video drivers. So mixing an nVidia card with an ATI card wouldn't be possible.

Two of one manufacturer or the other, yes, though they can't run SLI or Cross Fire. Only independently. IIRC, this was discovered accidentally by another member or two on the forum, as the same driver pulled up different cards by the same GPU maker.
 
nanofrog said:
I was under the strong impression you can only load a single set of video drivers. So mixing an nVidia card with an ATI card wouldn't be possible.
Click to expand...
It's quite possible, I've run a 7300GT and HD2600 XT simultaneously before.

As for why you'd use two graphics cards, IP is right, each display would have all the memory available to use - though I recall around half a year ago someone showing a graphic that had the second display only using 12MB of RAM or so. Up to you, really. If it's free it can't hurt.
 
Thanks for replies. I'm talking strictly about running this in OS X.

It just seems a bit of a waste to have a perfectly good video card just lying around in a box if I could be using it.

Instinctively it seems odd to use an nvidia and ATi but if someone has managed it in OSX then I'll give it a try and see if it feels any better.

Got to keep trying these things I guess.
 
I had an ATI X1900 and NVIDIA 7800GT in my PowerMac G5.

Do some benchmarks and tests on both as the primary display. The 8800GT is a great card but the ATi 3870 might do better in some applications. My old X1900 walked all over the 7800GT in OpenGL and Quartz.
OpenGL Extensions Viewer, CINEBENCH and Xbench are great for graphics benchmarks.
 
I use three of the 2600 cards to drive multiple monitors. I always assumed that the memory for each card was being used.

I have never tried to pool the resources of the cards, they are not exactly graphics powerhouses anyway...
 
It's definitely possible, considering you can even buy computers with multiple video cards (I'm referring to the MP here) directly from Apple.
 
I have 2 30" ADC's. One is driven by my ATI 3870 card. The other 30" is using my ATI 1900.

The difference in video performance, going from 2 ADC's and 1 card, and
a separate ATI card for each ADC is noticeable.
 
urchinboy said:
Thanks for replies. I'm talking strictly about running this in OS X.

It just seems a bit of a waste to have a perfectly good video card just lying around in a box if I could be using it.

Instinctively it seems odd to use an nvidia and ATi but if someone has managed it in OSX then I'll give it a try and see if it feels any better.

Got to keep trying these things I guess.
Click to expand...


You can load the MacPro with four different cards, giving you the option to drive eight thirty inch displays (provided your using suitable cards) Under MacOSX it'll be completely fine!! The system is intelligent enough to know what's the address used for each graphics card, therefore it'll attach each driver to each address.

However... Under Windows XP Pro and Vista, it appears to be fine for two cards. Can't say what if you installed four though.

I've tried both an ATI HD 2600 and as a side kick the 8800 GTS... and all is well! Technically speaking, the graphics card should deactivated if there's no display attached. Alternatively you can disable the card in the device manager!!
 
joegomolski said:
I have 2 30" ADC's. One is driven by my ATI 3870 card. The other 30" is using my ATI 1900.

The difference in video performance, going from 2 ADC's and 1 card, and
a separate ATI card for each ADC is noticeable.
Click to expand...

Umm... using two different cards, with two identical displays. Interesting.
I would of though colour matching (if you need it) would be more difficult, since one of the cards might reproduce colour slightly warmer or cooler. Have you notice this?
 
nanofrog: under both Leopard and XP, actually. XP fought it at first but eventually settled down. So you should be fine, urchinboy.
 
Mackilroy said:
nanofrog: under both Leopard and XP, actually. XP fought it at first but eventually settled down. So you should be fine, urchinboy.
Click to expand...
:cool:

Thanks for the clarification. :)
This might actually add a little hope for graphics options. ;) :p
 
I have a Mac Pro with an 8800GT and an ATI 2600HD, I run two 23" displays off the 8800GT and a single 20" display off the 2600.

Everything works great, but I wonder what's really going on when I run an OpenGL app, something like World of Warcraft. If I run the app in a window, I can drag it to any of the 3 displays. It even appears to run fine straddling between displays connected to the different video cards. It's.. amazing.

However, I wonder what's really going on. Which GPU is actually processing the OpenGL? If I drag the window from the Nvidia to the ATI, does it actually transfer the OpenGL workload to the new GPU? If I drag the window to the new display, quit and then restart the app, will that cause it to start up using the new GPU? Or, is it always using the "primary" GPU and just sending the window contents to the other video card for display?

Any insight appreciated :)
 
nanofrog said:
I was under the strong impression you can only load a single set of video drivers. So mixing an nVidia card with an ATI card wouldn't be possible.

Two of one manufacturer or the other, yes, though they can't run SLI or Cross Fire. Only independently. IIRC, this was discovered accidentally by another member or two on the forum, as the same driver pulled up different cards by the same GPU maker.
Click to expand...

Hi mate, this is only a problem that exists in Windows (Vista for sure, couldn't say about XP).
 
urchinboy said:
Thanks for all the replies everyone. I'm a whole lot clearer on it now. :)
Click to expand...

I had a great setup with a quad 2.0 using 1x ATI X1900XT and 2x nVidia 7300GT in OS X with a 22" widescreen running off each one in OS X.

Under Vista, only the X1900XT (center monitor for this reason!) was usable at all. I use Windows for gaming.
 
murphx said:
Hi mate, this is only a problem that exists in Windows (Vista for sure, couldn't say about XP).
Click to expand...
Mackilroy (couple of posts up) beat you to it. :p

He also indicated XP will work with cards from different manufacturers, though not without a tantrum or two. ;) :)
 
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