[J'nathus]

I'm having a bit of a debate with someone about this, and I can't find solid information.

This someone claims that ANY video card can be inserted into a Mac Pro because it possesses PCI-E slots (which is already a mistake). I know that there is the possibility of using any card IN WINDOWS . . . IN BOOT CAMP . . . but not ANY card in OS X, and that is where the glitches pop up.

There are posts out there claiming SLI is used on the Mac Pro, and there are posts that say even the newest one doesn't have a chipset that supports it (requiring either nForce or X58).

Anyone have any solid information on this?

[teflon]

Theres nothing like this in OSX. No driver support = no SLI.

But, and Im not 100%, I believe that the 3870 was crossfire compatible in windows. Now Crossfire and SLI work a bit differently, and I dont think that mac versions of NV cards are the SLI versions (if there is such a distinction), but it might be possible with a small selection of ATI/AMD cards.

Of course, Snow Leopard might well change all this, but there wont be anything before then.

[ltcommander.data]

Officially, SLI is a technology that can only be licensed by nVidia. nVidia's original stance was that their own chipsets contained special sauce in their hardware that allowed SLI to work. However, that isn't entirely true, since SLI has been cracked to work on other chipsets. With Nehalem and nVidia not having a license to make chipsets for it and suing Intel, nVidia has allowed a compromise by requiring motherboard makers with the X58 chipset to submit and pay nVidia to test the motherboard and certify it for SLI. No nVidia hardware required other than the graphics cards themselves. ATI has always been more open in allowing third-part chipsets to support Crossfire.

In any case, all this is for desktop and Windows. Mac Pros use server chips and chipsets and nVidia has never made a server chipset for Intel processors. I don't believe any server chipsets have been licensed for SLI either. So lack of SLI on the Mac Pro isn't exactly just an Apple problem. In Apple's own case, they also don't make SLI drivers for OS X. SLI drivers are actually a lot of work since you need to make custom SLI profiles to optimize for every individual game and application to really see the benefit. Without custom SLI profiles, games and applications can actually run slower with SLI than with a single card. Seeing Apple isn't exactly dedicated to Mac gaming, spreading driver development time even thinner on SLI profiles and Crossover profiles probably won't yield optimal results. Presumably, multiple GPUs will instead be taken advantage of through OpenCL, although it won't benefit games to increase raw fps directly.

[J'nathus]

There is a claim on one of the first results I see that SLI works on a Mac Pro.

I hear Crossfire works on many different Intel chipsets (even my motherboard supports it, to whatever end).

I read about the X58 SLI support. It's this mythical Mac Pro SLI support thing... it's like this kid swearing his 1980s Honda Civic can do a 9 second quarter mile. It's not impossible, but the evidence is sort of stacked against it.

[Tetsuya]

teflon, on June 14th 2009, 02:45 PM, said:

Theres nothing like this in OSX. No driver support = no SLI.

But, and Im not 100%, I believe that the 3870 was crossfire compatible in windows. Now Crossfire and SLI work a bit differently, and I dont think that mac versions of NV cards are the SLI versions (if there is such a distinction), but it might be possible with a small selection of ATI/AMD cards.

Of course, Snow Leopard might well change all this, but there wont be anything before then.

my 8800GT in my first-gen MacPro has the little 4 or-so pin connecter for SLI; my buddy actually put it in his machine (he runs two 8800GT's in SLI and has a MoBo that supports Tripple SLI) and got it working.

[Sneaky Snake]

Tetsuya, on June 15th 2009, 11:40 PM, said:

my 8800GT in my first-gen MacPro has the little 4 or-so pin connecter for SLI; my buddy actually put it in his machine (he runs two 8800GT's in SLI and has a MoBo that supports Tripple SLI) and got it working.

Having an SLI capable card doesn't mean that SLI will work. Firstly you need 2 PCI x16 slots, and secondly you need an nForce or X58 board, since nVidia only licensed those ones to have capable drivers etc. for SLI. I believe that none of the Mac Pros have those (except maybe the single CPU Nehalem ones - but I'm not sure).

Crossfire however is supported in bootcamp as confirmed by rob. he ran two 3870 in xfire while in bootcamp on the 2008 Mac Pro and I believe that it will work just fine in the new ones.

[J'nathus]

Sneaky Snake, on June 15th 2009, 09:06 PM, said:

Having an SLI capable card doesn't mean that SLI will work. Firstly you need 2 PCI x16 slots, and secondly you need an nForce or X58 board, since nVidia only licensed those ones to have capable drivers etc. for SLI. I believe that none of the Mac Pros have those (except maybe the single CPU Nehalem ones - but I'm not sure).

Crossfire however is supported in bootcamp as confirmed by rob. he ran two 3870 in xfire while in bootcamp on the 2008 Mac Pro and I believe that it will work just fine in the new ones.

The Mac Pros have the multiple PCI slots, as you can get certain cards times 2 and 3 (and times 4 I thought at one point). That must've served a purpose, but I don't know what (in OS X I mean). Getting multiple cards connected isn't the challenge... I thing actually getting SLI working properly on a Mac Pro is the myth that I want to debunk, but evidence is sketchy. One guy said he killed his GTX 295 that he'd been running in his Mac Pro . . . That's something that tells me without a doubt that 'any PCI-E card does NOT work in a Mac Pro.' If they did, there wouldn't be Mac specific editions.

In any case, the guy I was debating with went from "I have plenty of friends running SLI on their Mac Pro" . .. to "I have one friend" . . to "I don't know what he's really running or how he's doing it."

I argue not out of malice or self-righteousness, but because I like the stimulation. I like being forced to look things up I hadn't thought about before and then learning a bit in the process. It's kind of like when you're in school and you find a topic in a class interesting. Yes it interests you, but would you really have looked it up without the class to 'make' you do it?

[The Liberator]

If you cannot do SLI with the Mac Pro, then why has Apple done this? Maybe it still somehow works well enough anyway?

Liberator.

[Janichsan]

The Liberator, on June 16th 2009, 11:09 AM, said:

If you cannot do SLI with the Mac Pro, then why has Apple done this?

That's why:

Quote

Add more than one card to power an array of displays simultaneously for visualization projects and large display walls.

[The Liberator]

Ah, I see.

Thanks, Liberator.

[Tetsuya]

Sneaky Snake, on June 15th 2009, 09:06 PM, said:

Having an SLI capable card doesn't mean that SLI will work. Firstly you need 2 PCI x16 slots, and secondly you need an nForce or X58 board, since nVidia only licensed those ones to have capable drivers etc. for SLI. I believe that none of the Mac Pros have those (except maybe the single CPU Nehalem ones - but I'm not sure).

Crossfire however is supported in bootcamp as confirmed by rob. he ran two 3870 in xfire while in bootcamp on the 2008 Mac Pro and I believe that it will work just fine in the new ones.

that wasn't the point of my post at all.

Someone said they didnt know if the Mac NV cards even had the SLI connectors in the first place; i confirmed the 8800GT for the first-gen Pro's does, at least.

[J'nathus]

Yes, but DOES SLI work on a Mac Pro!?!?!

I'm going to go out on a limb and guess that it's not, but I still haven't managed proof of same.

[teflon]

Sorry, that was me that wasn't sure.
Interesting that it has the connector. Either Apple has plans to use it at some point, or its just a reference board being used. Either way it doesn't matter since the MP cant use it.

[Sneaky Snake]

J, on June 16th 2009, 12:34 PM, said:

Yes, but DOES SLI work on a Mac Pro!?!?!

I'm going to go out on a limb and guess that it's not, but I still haven't managed proof of same.

In OS X - no, I'm positive of that

In bootcamp - maybe on the new 2009 Mac Pros since they are a Nehalem chipset of Mobo but since they are dual socket i doubt whoever made them bothered to pay for and include SLI support. Especially since these boards were only available in Mac Pros for a while (PC companies didn't have access to a dual socket Nehalem until a later date).

Short Answer: No

Quote

that wasn't the point of my post at all.

Someone said they didnt know if the Mac NV cards even had the SLI connectors in the first place; i confirmed the 8800GT for the first-gen Pro's does, at least.

Ah I see, sorry for the confusion.

[Tetsuya]

AFAIK, Intel makes the motherboards for the Pro's.

[Sneaky Snake]

Tetsuya, on June 17th 2009, 07:06 PM, said:

AFAIK, Intel makes the motherboards for the Pro's.

Pretty much positive that it doesn't support SLI then

[bobbob]

I'm pretty sure Foxconn makes Intel's boards. Or at least someone other than Intel does.

[J'nathus]

Sneaky Snake, on June 17th 2009, 04:49 PM, said:

Pretty much positive that it doesn't support SLI then

Well, that's not proof positive, as the Intel X58 chipset will work with SLI. The trick becomes finding out what chipset the Mac Pro is using.

[teflon]

Well, since its still Xeons and Apple, it looks like itll be intel's 5520 chipset. It matches up with the specs better than the 5500, since it has two 16x PCIe slots instead of just one and is dual socket, unlike the X58.

From that we might be able to glean a little bit more info somewhere...

[Sneaky Snake]

Well I did some googling and it seems that there is no SLI support, one guy I came across was wanting to flash the board to have an SLI cheipset, a review said the following

Quote

The S5520SC motherboard has six DDR 3 memory slots for each of the two sockets and it did a solid job for us. But it's an uninspiring motherboard for a reviewer working with a new processor. The twin graphics slots support CrossFire but not SLI,

The 5520 is apparently the mobo in the Mac Pro