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reader50 · Aug 9, 2006, 02:38 PM

From this tech documentation from Apple:

Note: The Mac Pro does not simultaneously support an ATI graphics card and an Nvidia graphics card.

This is a technote covering Mac video options, this section covers graphics cards for the Mac Pro. The document was last updated August 8, 2006.

That little note caught my eye. I don't know what it means, and there was no further info mentioned. Does plugging in cards from both vendors mean that only the cards from one company will be enabled? I don't see any technical reason why that would happen.

mac128k-1984 · Aug 9, 2006, 02:39 PM

To my uneducated eyes that kind of makes sense. You have device drivers loaded for a specific device, having two seperate cards from different companies could cause issues.

OreoCookie · 03:35 PM

I don't think this is a limitation of the Mac Pro. I haven't heard of anyone mixing different brands of graphics cards in the pc world (apart from pci cards and such).

However, I will ask some pc people I know …

mduell · Aug 9, 2006, 03:35 PM

Can you mix GPU brands on PPC PowerMacs?
This is either a limitation of OSX (possibly only on Intel), or something weird with PCI Express. I've had PCs running Windows in the past with ATi and nVidia graphics cards (one on AGP, one on PCI) running simultaneously.

Steve Bosell · Aug 9, 2006, 03:45 PM

Originally Posted by mduell

Can you mix GPU brands on PPC PowerMacs?
This is either a limitation of OSX (possibly only on Intel), or something weird with PCI Express. I've had PCs running Windows in the past with ATi and nVidia graphics cards (one on AGP, one on PCI) running simultaneously.

I had a G3 tower running OS9 with two differend video cards, ATI and a Voodoo3, both PCI.

OreoCookie · Aug 9, 2006, 03:50 PM

Originally Posted by mduell

Can you mix GPU brands on PPC PowerMacs?
This is either a limitation of OSX (possibly only on Intel), or something weird with PCI Express. I've had PCs running Windows in the past with ATi and nVidia graphics cards (one on AGP, one on PCI) running simultaneously.

Mixing AGP and PCI graphics cards has never an issue, that works just fine (been there, done that with PCs, too). On the other hand, have you heard of a pc user mixing PCIe cards? I haven't. I guess it is connected to the fact that both companies' drivers now support (expect?) multi graphics cards setups of the same manufacturer.

So no, I don't think it's a limitation of OS X. It must be either the drivers or the hardware (in which case it wouldn't work on Windows or Linux either).

mduell · Aug 9, 2006, 06:03 PM

I can't even find anyone on Google who has tried to mix ATi and nVidia on PCIe...

Tomchu · Aug 9, 2006, 07:04 PM

Such a setup works fine in Windows XP. I just tried it on a Core 2 test station at work. The first PCI-E slot has a GeForce 7800 GT in it, the second slot has a Radeon X1900 XT. The motherboard is an ASUS P5B Deluxe.

Drivers for both cards are installed, and I can extend the desktop onto the second monitor.

Clearly it's not a limitation of either Windows, the drivers, or the hardware. I would say OS X's window server probably can't handle loading two completely different drivers and using them both at the same time.

OreoCookie · Aug 9, 2006, 07:20 PM

But that's what the window server does for so many years now: using two different drivers for two different graphics cards. That leaves us with the option that the limitation is in the drivers for the graphics cards.

andreas_g4 · Aug 9, 2006, 07:30 PM

Originally Posted by Tomchu

I would say OS X's window server probably can't handle loading two completely different drivers and using them both at the same time.

How would I rant if it were a Windows issue…

Tomchu · Aug 9, 2006, 07:39 PM

Originally Posted by OreoCookie

But that's what the window server does for so many years now: using two different drivers for two different graphics cards.

Not at the same time, in OS X -- at least, I've never seen or heard of it being done. Anyone care to try putting an ATI and NVIDIA card into their PCI-E G5?

Originally Posted by OreoCookie

That leaves us with the option that the limitation is in the drivers for the graphics cards.

I think it's cute that you're defending OS X even though you don't have the facts, but I highly doubt it's the drivers. A video driver doesn't care what other video drivers are loaded or on the system. It talks to one or more of the kind of cards that respond to its probing/initialization routines, and that's it.

Andreas: I'm sure everyone here would rant if Windows didn't allow it, but it does. I don't hear any ranting, though -- I just hear defense. ;-)

Laurence · Aug 9, 2006, 08:48 PM

In fact on our video workstation at work (Dell Precision 6xx) we couldn't get two NVidia cards to work properly so we just put in an old FireGL ATI card and it worked fine in conjunction with a Quadro FX 1400. This means it is definitely an OS X issue. I seriously doubt it is a hardware issue as I'm sure a similar Intel motherboard is used in many PC systems. I guess the best way to find out for sure is to wait until Bootcamp works on the MacPro and test it.

mduell · Aug 9, 2006, 09:03 PM

Originally Posted by Tomchu

Not at the same time, in OS X -- at least, I've never seen or heard of it being done. Anyone care to try putting an ATI and NVIDIA card into their PCI-E G5?

AFAIK there aren't any ATi PCIe cards for G5s yet.

tobyg · Aug 9, 2006, 09:14 PM

Originally Posted by Tomchu

Such a setup works fine in Windows XP. I just tried it on a Core 2 test station at work. The first PCI-E slot has a GeForce 7800 GT in it, the second slot has a Radeon X1900 XT. The motherboard is an ASUS P5B Deluxe.

Drivers for both cards are installed, and I can extend the desktop onto the second monitor.

Clearly it's not a limitation of either Windows, the drivers, or the hardware. I would say OS X's window server probably can't handle loading two completely different drivers and using them both at the same time.

Here is what I'm interested in.

My PC currently has a 7800 GTX. Good card for gaming.

If I leave the 7300GT in a 8x slot on the mac pro, put the 7800 GTX in the 16x slot, I wonder if I can boot up into OSX with the 7300GT (and if it sees the 7800 GTX, great, if not, thats fine too) and then use Bootcamp, boot XP and use the 7800 GTX as my default card. That way I can at least get faster gaming without having to wait for the x1900 XT (way back-ordered right now).

I could get rid of my gaming PC all together then.

Tomchu · Aug 9, 2006, 09:58 PM

tobyg: Here are my thoughts on your question --

1. Windows XP allows you to set which monitor is your primary monitor, which essentially also tells 3D applications that don't let you pick a display adapter to work on which adapter to default to. So yes, with two video cards in a system, it is possible to tell Windows which one to make use of.

2. Your PC's 7800 GTX will most likely not work in the Mac Pro because as far as I know, the Mac Pros will require EFI-based video adapters. Video adapters in PCs now are BIOS-based.

3. The Mac Pro most likely does not have a PCI-Express power plug (the 6-pin kind). Not knowing any better currently, I would say Apple has probably come up with something near the base of the card for power, so as to maintain the cable-less look. They could also technically be pumping all the power over PCI-Express. The 7300 GT doesn't require external power, but the X1900 does.

mduell · Aug 9, 2006, 10:44 PM

Originally Posted by Tomchu

2. Your PC's 7800 GTX will most likely not work in the Mac Pro because as far as I know, the Mac Pros will require EFI-based video adapters. Video adapters in PCs now are BIOS-based.

3. The Mac Pro most likely does not have a PCI-Express power plug (the 6-pin kind). Not knowing any better currently, I would say Apple has probably come up with something near the base of the card for power, so as to maintain the cable-less look. They could also technically be pumping all the power over PCI-Express. The 7300 GT doesn't require external power, but the X1900 does.

2. I don't know that there's really a difference there. I think it would have been rather shortsighted to design EFI without some backward compatibility, like the CSM that allows you to emulate a BIOS for operating systems that weren't written for EFI.

3. In the service manual, there are directions for removing a video card with a "booster cable." On the X1900XT depicted, the cable looks an awful lot like a PCIe power plug. Although they certainly could have gone with a similar-but-proprietary plug, I don't see much incentive to it.

tobyg · Aug 9, 2006, 11:10 PM

Originally Posted by Tomchu

tobyg: Here are my thoughts on your question --

1. Windows XP allows you to set which monitor is your primary monitor, which essentially also tells 3D applications that don't let you pick a display adapter to work on which adapter to default to. So yes, with two video cards in a system, it is possible to tell Windows which one to make use of.

2. Your PC's 7800 GTX will most likely not work in the Mac Pro because as far as I know, the Mac Pros will require EFI-based video adapters. Video adapters in PCs now are BIOS-based.

3. The Mac Pro most likely does not have a PCI-Express power plug (the 6-pin kind). Not knowing any better currently, I would say Apple has probably come up with something near the base of the card for power, so as to maintain the cable-less look. They could also technically be pumping all the power over PCI-Express. The 7300 GT doesn't require external power, but the X1900 does.

Yeah I know all that about XP... and as far as the EFI/BIOS thing... I don't know if that's true. Some of the stuff I've heard is people getting X1600 XT cards running on hacked macs, and of course also GMA 900/950. Also, someone on another forum got a Mac Pro and installed the standard NVidia drivers and it detected the 7300GT. If that is true, most likely it should work the other way around. Doesn't mean the nvidia drivers will work with the 7800 GTX because they are based on different chips I believe, but its not impossible.

Also, take a look at the second to last picture here:

http://www.powermax.com/articles_rev...icle.php?id=32

You can see the additional power cable going in. AFAIK, and from what I've seen, they have not modified the PCIe slot so those cards will still need extra power from somewhere.

Tomchu · Aug 9, 2006, 11:30 PM

2. Apple has no reason to implement the EFI firmware on a Mac Pro so as to allow legacy BIOS-based video cards. The video BIOS is initialized so early on in the boot process that I'm not even sure a CSM module would be able to enable such functionality.

3. Oh, cool. I guess someone will have to post close-up pictures.

Chuckit · Aug 9, 2006, 11:57 PM

So just to be clear: If you buy a stock model and decide later that you want a Radeon X1900, you're SOL since the non-Apple ones are BIOS-based? That kind of sucks.

tobyg · Aug 10, 2006, 12:26 AM

Originally Posted by Chuckit

So just to be clear: If you buy a stock model and decide later that you want a Radeon X1900, you're SOL since the non-Apple ones are BIOS-based? That kind of sucks.

No you're not SOL, but you are going to be out 500 bucks or so.

http://store.apple.com/1-800-MY-APPL...nMore=MA631Z/A

Chuckit · Aug 10, 2006, 12:39 AM

Oh, I see. Heh, that sucks almost as bad. Thanks for pointing that out; I hadn't seen that.

OreoCookie · Aug 10, 2006, 02:10 AM

Originally Posted by Tomchu

Not at the same time, in OS X -- at least, I've never seen or heard of it being done. Anyone care to try putting an ATI and NVIDIA card into their PCI-E G5?

Exactly the point, I haven't heard of anyone doing it with PCIe graphics cards. AGP and PCI, yes, no problem so far.

Originally Posted by Tomchu

I think it's cute that you're defending OS X even though you don't have the facts, but I highly doubt it's the drivers. A video driver doesn't care what other video drivers are loaded or on the system. It talks to one or more of the kind of cards that respond to its probing/initialization routines, and that's it.

Defense? It does work when you mix AGP and PCI graphics cards, because that's what many people in this forum did to connect more monitors. It's just a fact that this works, and hence it's unlikely a limitation of the window server.

nforcer · Aug 10, 2006, 06:22 AM

Originally Posted by Chuckit

Oh, I see. Heh, that sucks almost as bad. Thanks for pointing that out; I hadn't seen that.

I agree. I'm really hoping someone figures out a way to use PC vid cards with our new machines. If not I'll just wait until the next rev of mac pros (or the one after) which will hopefully have new vid cards that we can also use. I'm not a real fan of ATI right now but the Quattro isn't a desirable option, either.