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BWSchultz · Jan 8, 2008, 01:24 PM

I wish I understood video cards a little better. I have an original Power Mac G5 and my only regret with the machine was getting a poor Graphics card and then having to upgrade later. With these new cards from Apple, I'm trying to get a handle on it. I certainly don't need a $2800 graphics card so let's safely toss the FX5600 to the side. Sheesh.

Does the MacPro support Crossfire and SLI technologies? I'm guessing Yes to crossfire but no to SLI. As best I can tell, these technologies allow the user to pair two graphics cards together to improve performance.

Does the 2 x 2600 XT use Crossfire technology? Is Nvidia 8800GT better than the 2x 2600XT config? Could I do a 2x Nvidia 8800GT config with SLI? Thanks for your help. I'm not buying one soon but I'd like to understand the underlying tech of these cards.

Macadvo · Jan 8, 2008, 01:34 PM

I don't think Apple supports either of these two technologies in OS X. I've read that they will work under windows though.

BWSchultz · Jan 8, 2008, 01:41 PM

Well, ok. So doing the 2x 2600XT config just adds the capability for more monitors? What advantage/disadvantage does that have vs. crossfire capability? If I did the 2x 2600XT, you're saying that they would be "crossfired" in Vista/XP ?

Macadvo · Jan 8, 2008, 01:46 PM

Yes that's what I'm saying, Crossfire and SLi require both hardware AND driver support. I'm not 100% sure if the current Mac Pro supports either Crossfire or SLi in hardware but I a sure Apple have yet to offer driver support for them.

If you search google for Mac Pro chipset support for crossfire/sli and see what you get...

Leonard · Jan 8, 2008, 07:13 PM

As far as I know, you can only run SLI on a Mac Pro in Windows with two of the PCIe slots defined as 8x lanes (this is based on the old Mac Pro). It requires a hack (as Intel boards don't support SLI without a hack) and it requires a flexible SLI bridge. I haven't heard of anyone getting Crossfire to work.

MacOS X so far has no support for SLI.

mduell · Jan 8, 2008, 07:17 PM

The Mac Pro may support Crossfire, but OS X doesn't so unless you're running Windows it doesn't really matter; there is no SLI support.

Buy the 8800GT and enjoy it.

Cadaver · Jan 8, 2008, 09:32 PM

I don't think I've read where anyone is successfully, stably running either SLI (nVidia) or CrossFire (ATI) on a Mac Pro (in Windows, of course). Plus, to have any real benefit, you'd need at a minimum two 16x PCIe slots; the Mac Pro has only one. Running two cards in 8x mode is kinda silly.

MacOS X has no support for SLI/CrossFire at all.

On the Mac, more graphics cards = more monitors. Does not give you faster graphics on one monitor.

As usual, Apple's market is not uber-high-end gamer graphics with SLI setups. Plus, even on the Windows/PC side, I don't think there are any Xeon motherboards that support SLI/CrossFire; only non-Xeon single-processor boards.

mduell · Jan 8, 2008, 10:10 PM

Originally Posted by Cadaver

I don't think I've read where anyone is successfully, stably running either SLI (nVidia) or CrossFire (ATI) on a Mac Pro (in Windows, of course). Plus, to have any real benefit, you'd need at a minimum two 16x PCIe slots; the Mac Pro has only one.

The new Mac Pro has two 16x PCI Express 2.0 slots.

eggman · Jan 9, 2008, 01:09 AM

Originally Posted by mduell

The new Mac Pro has two 16x PCI Express 2.0 slots.

That's not what Apple's site says:

PCI Express expansion

Three open full-length PCI Express expansion slots

One PCI Express 2.0 x16 slot
Two PCI Express x4 slots

All slots provide mechanical support for 16-lane cards
300W combined maximum for all PCI Express slots

dimmer · Jan 9, 2008, 01:18 AM

The keyword there is "Open" - the first slot is fitted with the graphics card of your choice, and would be a second PCI Express 2.0 x16 slot.

eggman · Jan 9, 2008, 03:27 AM

Originally Posted by dimmer

The keyword there is "Open" - the first slot is fitted with the graphics card of your choice, and would be a second PCI Express 2.0 x16 slot.

I stand corrected!
Very cool.

PaperNotes · Jan 9, 2008, 08:05 AM

There are no problems running Xeons with SLI graphics on Asus motherboards.

MacosNerd · Jan 9, 2008, 08:45 AM

Originally Posted by PaperNotes

There are no problems running Xeons with SLI graphics on Asus motherboards.

your point being?

Cadaver · Jan 9, 2008, 01:56 PM

Originally Posted by PaperNotes

There are no problems running Xeons with SLI graphics on Asus motherboards.

But other than the Skulltrail (or whatever its called) motherboard/chipset, which I'm not sure is available yet, are there any Intel-branded motherboards that support two Xeons and SLI or Crossfire? AFAIK, no.