Crossfire for nMP on Windows / Boot Camp

drunkn

macrumors member
Original poster
Aug 12, 2010
31
0
I know crossfire isn't a thing for OS X, but based on some quick googling I've seen mild success with previous Mac Pros and getting Crossfire to work.

Has anyone read anything about a review that has done some Windows / Boot Camp benchmarking, and were they able to Crossfire?

Thanks
 

deconstruct60

macrumors G3
Mar 10, 2009
8,901
1,753
I know crossfire isn't a thing for OS X, but based on some quick googling I've seen mild success with previous Mac Pros and getting Crossfire to work.
Crossfire that requires a AMD proprietary socket is about as likely supported on these Apple custom designed cards as an extra hole drilled in the side of the Mac Pro case. There is little reason Apple would go through effort to put non default sockets on their GPU card that only works in Windows.
 

Radiating

macrumors 65816
Dec 29, 2011
1,018
7
Crossfire that requires a AMD proprietary socket is about as likely supported on these Apple custom designed cards as an extra hole drilled in the side of the Mac Pro case. There is little reason Apple would go through effort to put non default sockets on their GPU card that only works in Windows.
Rumor has it that it's supported. There is no proprietary socket, it's all done through pci express. Apple would have to go out of their way to disable it.
 

slughead

macrumors 68040
Apr 28, 2004
3,104
236
Rumor has it that it's supported. There is no proprietary socket, it's all done through pci express. Apple would have to go out of their way to disable it.
Crossfire is on by default in new mac pros bootcamp.
holy sh#t
How do you find such information?
I've heard also from Apple (although I have not verified it) Crossfire should be available in Boot Camp.
Citation needed.

The latest Tahiti video cards (280x) for PC still require an Xfire bridge--can't be done through PCIe alone. Only the Hawaii cards have Xfire through PCIe AFAIK.

I'm not saying it isn't true, I just don't think it's likely and I'll need to see verification before I believe it.

I'd also like to see how these cards are recognized in Windows and if they have the Workstation card performance benefits--or are they just 7970's with more RAM. According to the dissecting of the latest EFI update, they don't even have ECC.
 

Cubemmal

macrumors 6502a
Jun 13, 2013
824
1
Citation needed.
Agree

The latest Tahiti video cards (280x) for PC still require an Xfire bridge--can't be done through PCIe alone. Only the Hawaii cards have Xfire through PCIe AFAIK.
Correct, but I believe that's simply due to the memory controllers on the card, from what I remember from the AMD commentary. So it's possible that Apple included this technology.
 

wheelhot

macrumors 68020
Nov 23, 2007
2,080
249
I'd also like to see how these cards are recognized in Windows and if they have the Workstation card performance benefits--or are they just 7970's with more RAM. According to the dissecting of the latest EFI update, they don't even have ECC.
I thought to have the word FirePro in its name requires it to have ECC memory?
 

ZnU

macrumors regular
May 24, 2006
171
0
The latest Tahiti video cards (280x) for PC still require an Xfire bridge--can't be done through PCIe alone. Only the Hawaii cards have Xfire through PCIe AFAIK.
Note that we don't know there isn't a CrossFire bridge. These cards aren't in any standard form factor. The connectors at the bottom could have additional pins for this as well as standard PCIe. I admit it's unlikely Apple would bother for a feature OS X doesn't support, but it can't be ruled out. Maybe they're planning to support it in some way in the future, or maybe they just see good performance in Windows games as a nice perk for pros who want to unwind at the end of the day or whatever.

Also, these are custom cards. People tend to use the terms 'GPU' and 'graphics card' interchangeably, but that distinction might matter here. Do we know that Tahiti not doing CrossFire over PCIe is actually a GPU limitation, or is CrossFire implemented by other components on the board? If the latter, Apple could have done basically anything here.
 

Cubemmal

macrumors 6502a
Jun 13, 2013
824
1
I was planning on putting Windows on an external disk, but maybe I won't bother. I have a 2009 MP serving Windows duty, and the new 9750 card handles the one game I play just fine (LOTRO).

Even getting a good external thunderbolt SSD enclosure is problematic, all the ones I find have fans or I don't like them for one reason or another. OWC would do well to create a TB box which takes PCIe SSD, and offer PCIe upgrades. That way you can upgrade and put your old one external.
 

drunkn

macrumors member
Original poster
Aug 12, 2010
31
0
Seems like there's enough nMPs out there now to get some someone to test this for us...

Anyone know somebody yet? Mine is still in the processing phase (6core d700), but if no one let's us know by then I'll report back here.
 

deconstruct60

macrumors G3
Mar 10, 2009
8,901
1,753
Note that we don't know there isn't a CrossFire bridge. These cards aren't in any standard form factor. The connectors at the bottom could have additional pins for this as well as standard PCIe.
they also have to run the DisplayPort outputs through this bottom connector. PCI-e SSD connectdion ... again through this connector.

that doesn't seem to leave copious spare room for Crossfire pins as well. The connector already has 3 functions already. Adding 4th is just complexity that just isn't needed.


I admit it's unlikely Apple would bother for a feature OS X doesn't support, but it can't be ruled out. Maybe they're planning to support it in some way in the future,
Doubtful in the future. More likely Apple is going to have another design bake off and there may be a Nvidia GPUs in the next card. I highly doubt Apple wants to sink engineering resources into keeping both of those proprietary solutions going forward.

"Crossfire"/"SLI" over standard PCI-e i can see Apple getting behind but not these proprietary, vendor lock-in, sockets. Apple is far more likely going to want situations where they make the vendors compete and pick whatever winner best meets their criteria on each iteration.


or maybe they just see good performance in Windows games as a nice perk for pros who want to unwind at the end of the day or whatever.
If there are AMD drivers that work over PCI-e v3 fine. But I suspect that these are going to be signficantly far out of the Windows gaming market mainstream. ( AMD has had "Crossfire over PCI-e drivers" before that didn't go very far. )


Do we know that Tahiti not doing CrossFire over PCIe is actually a GPU limitation, or is CrossFire implemented by other components on the board? If the latter, Apple could have done basically anything here.
The critical issue is pathway to/from Memory to the PCI-e bus. So the GPU is the primary piece involved here as to whether the performance is "just as good as" the other solution over the proprietary slots.
 

goMac

macrumors 604
Apr 15, 2004
7,147
1,167
Citation needed.
I was told by a source at Apple at the time the Mac Pro was announced that Crossfire would be supported under Windows. But as I mentioned, that's not a verification.

I admit it's unlikely Apple would bother for a feature OS X doesn't support, but it can't be ruled out. Maybe they're planning to support it in some way in the future, or maybe they just see good performance in Windows games as a nice perk for pros who want to unwind at the end of the day or whatever.
Lot's of fuzziness here:
- OS X does have an API that lets developers use multiple GPUs at the same time for OpenGL. It's possible that they've either added a way in OS X or are looking at a way to use a bridge to speed up this API. Note that this API isn't as automatic as Crossfire, but it lets developers accomplish the same thing. Usually this API works by moving resources over the PCI-E bus.
- Apple, as noted, may want to keep their options open for adding Crossfire in the future.
- Apple also knows Bootcamp is a real use case, and they may want to support it to it's fullest.
 

deconstruct60

macrumors G3
Mar 10, 2009
8,901
1,753
- OS X does have an API that lets developers use multiple GPUs at the same time for OpenGL. It's possible that they've either added a way in OS X or are looking at a way to use a bridge to speed up this API. Note that this API isn't as automatic as Crossfire, but it lets developers accomplish the same thing. Usually this API works by moving resources over the PCI-E bus.
- Apple, as noted, may want to keep their options open for adding Crossfire in the future.
But the future of Crossfire is the PCI-e mechanism. The R9 290X (Hawaii ) dumps the proprietary connector. Not sure what motives Apple to sink a tons of new effort at this point into a socket that is being decommissioned.

That would actually also be an indicator that this version's Mac Pro GPU connector might be a 'dead ender" connection. Apple having the own connector is one thing. A connector that is going to flap in the wind with every major GPU card design bake off is another.


- Apple also knows Bootcamp is a real use case, and they may want to support it to it's fullest.
Long term AMD is moving to where Apple is (inter card communication over PCI-e). Over time they will. This short term optimization probably buys as much drama with 3rd party cards in 2009-2012 Mac Pros piggy backing off of it with perhaps unauthorized kludges as it probalby helps.

With the coming advent of Steam machines and the mature gamer focused PC market .... hard core max bootcamp gamer crowd isn't all that large and not getting any bigger over time.
 

goMac

macrumors 604
Apr 15, 2004
7,147
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But the future of Crossfire is the PCI-e mechanism. The R9 290X (Hawaii ) dumps the proprietary connector. Not sure what motives Apple to sink a tons of new effort at this point into a socket that is being decommissioned.

That would actually also be an indicator that this version's Mac Pro GPU connector might be a 'dead ender" connection. Apple having the own connector is one thing. A connector that is going to flap in the wind with every major GPU card design bake off is another.




Long term AMD is moving to where Apple is (inter card communication over PCI-e). Over time they will. This short term optimization probably buys as much drama with 3rd party cards in 2009-2012 Mac Pros piggy backing off of it with perhaps unauthorized kludges as it probalby helps.

With the coming advent of Steam machines and the mature gamer focused PC market .... hard core max bootcamp gamer crowd isn't all that large and not getting any bigger over time.
According to AMD, PCI-E 3.0 is the advancement that let's them drop the Crossfire bridge.

If that's true, I don't see any reason Apple couldn't have just forced the same behavior the 290x has on the D300/D500/D700.
 

MH01

Suspended
Feb 11, 2008
12,107
9,298
According to AMD, PCI-E 3.0 is the advancement that let's them drop the Crossfire bridge.

If that's true, I don't see any reason Apple couldn't have just forced the same behavior the 290x has on the D300/D500/D700.
The limitation being that the D300-D700 are not based on the 290x. Only the 290x does not require a bridge.

I'm really hoping for crossfire support in windows. So let's hope AMD/Apple pulled it off
 

goMac

macrumors 604
Apr 15, 2004
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The limitation being that the D300-D700 are not based on the 290x. Only the 290x does not require a bridge.

I'm really hoping for crossfire support in windows. So let's hope AMD/Apple pulled it off
Right, I'm aware that the 290x is the only card currently certified for bridge-less Crossfire, but I'm not sure why you couldn't technically do bridge-less Crossfire on a 280x. PCIe 3.0 is the technical requirement for the new Crossfire technology, which the Mac Pro has.
 

MH01

Suspended
Feb 11, 2008
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Right, I'm aware that the 290x is the only card currently certified for bridge-less Crossfire, but I'm not sure why you couldn't technically do bridge-less Crossfire on a 280x. PCIe 3.0 is the technical requirement for the new Crossfire technology, which the Mac Pro has.
Id assume its to do with the video cards as well.

PCIe 3.0 was released with the 79XX cards were out, they all needed bridges, so I assume it was not that easy/possible. And the 280 is effectively a 7970.

I could be wrong though
 

Cubemmal

macrumors 6502a
Jun 13, 2013
824
1
According to AMD, PCI-E 3.0 is the advancement that let's them drop the Crossfire bridge.

If that's true, I don't see any reason Apple couldn't have just forced the same behavior the 290x has on the D300/D500/D700.
Yes it's PCIe 3, with the addition of some memory controllers that do the DMA. This costs money and effort on Apples part and old companies like that don't do anything without a reason, so why would they incorporate that? The only active reason would be they want to allow people to Crossfire under Windows, but Apple doesn't have a lot of motivation for that.

The passive reason is that it would just be easier to incorporate it than leave it out. They're borrowing IP heavily from AMD on this one, both hardware design and actual drivers. Its possible that they just got the memory IP from AMD. However it's all new technology, only released the month before.

I don't know ... doesn't seem likely that it would be in there, it's more Apple's style to leave something like that out regardless. Also since there's no mention in the support documents, that would seem to indicate it too.
 

slughead

macrumors 68040
Apr 28, 2004
3,104
236
The limitation being that the D300-D700 are not based on the 290x. Only the 290x does not require a bridge.

I'm really hoping for crossfire support in windows. So let's hope AMD/Apple pulled it off
Right, I'm aware that the 290x is the only card currently certified for bridge-less Crossfire, but I'm not sure why you couldn't technically do bridge-less Crossfire on a 280x. PCIe 3.0 is the technical requirement for the new Crossfire technology, which the Mac Pro has.
The 7970 Was released 2 years ago as "the first PCIe 3.0 16x graphics card." It most certainly requires a bridge, even with PCIe 3.0.

The advent of PCIe 3.0 alone is not enough, there are other hardware changes on the card necessary for Crossfire without a bridge. Regardless of the technical reasons why, the 280x still requires a bridge--as do all Tahiti-based cards.

In fact, the only indicator I've seen that the Dx00 will have crossfire without a bridge is your (as in YOU, goMac's) supposed inside source within Apple. There isn't much reason to think Apple went out of their way to include something not typically found in the card they downclocked, disabled, repackaged, and crammed into the iTube. Crossfire isn't even required for a lot of MultiGPU pro apps. Seems like they'd have to go even further out of their way for a use-case they don't even recognize (ie Gaming).
 
Last edited:

Voley

macrumors regular
Oct 24, 2013
111
161
Many people have already received their Mac Pro, is it hard to just test it?
 
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