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2 x GTX 680 Mac Editions in MacPro4,1?

5

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macrumors regular
Original poster
May 28, 2009
180
2
Is it possible to install two GTX 680 Mac Editions in a MacPro4,1?

If so, what performance scalability (interested primarily in After Effects CUDA performance) might be expected with 2 GTX 680s vs just 1?

Will the performance equal that of a GTX 690 (again, CUDA performance in After Effects)?

Last, are there any power, noise, or heat issues that I should consider?

Thanks much!!

Jonathan
 
I believe that SLI would only work in windows - also as I'm sure you know you'll need an external power supply
 
Brownmastiff1 said:
I believe that SLI would only work in windows - also as I'm sure you know you'll need an external power supply
Click to expand...

Actually, I haven't upgraded my Mac Pro's in a long time, so this is actually "new" news to me, thanks.

So I suppose this means SLI (scaleable link interface) would only work in Bootcamp?

And didn't realize I would need an external power supply for a 2nd card. I thought as long as the card is Mac qualified, the 2nd card could simply go into an open PCIe slot using the Mac Pro's native power supply in the PCIe bus . . .

There goes that idea!
 
Each card uses two 6 pin power leads so you would have to have another PS or take a risk and run the 2nd card off the SATA power leads to DVD drives! Don't recommend that at all.
 
Question in regards to this other than power would this work in OSX without major issues? and would a Cuda aware app or an OpenCL aware app be able to leverage both cards?
 
KBS756 said:
Question in regards to this other than power would this work in OSX without major issues? and would a Cuda aware app or an OpenCL aware app be able to leverage both cards?
Click to expand...

If both cards are being supplied with enough power, there's really no reason why they wouldn't both function by OS X. People will often do this to drive multiple displays.

But far as your OpenCL/CUDA question is concerned, it really depends on the application. For example, Adobe Premiere (which uses CUDA for realtime playback acceleration) will only see/use the CUDA card that your primary display is connected to. I believe the same is true for FCP X's OpenCL acceleration.

DaVinci Resolve is capable of scaling across multiple CUDA GPUs (provided that one graphics card is dedicated to its GUI), but on the Mac Pro, that usually requires a PCIe expansion chassis (like a Cubix).

And I don't think SLI support will ever come to OS X. There's practically zero demand. Outside of games (most of which are Windows only), a very small niche of pro applications can actually use SLI.
 
CaptainChunk said:
For example, Adobe Premiere (which uses CUDA for realtime playback acceleration) will only see/use the CUDA card that your primary display is connected to.
Click to expand...

For what little it may be worth, this is supposed to change with the upcoming release of Premiere Pro Next (May timeframe). One of the features being added is the ability to utilize multiple GPUs for exports.

jas
 
GTX 680 2GB needs 195W and 38A

About MacPro4,1 Everymac says:

*This model has four full-length PCI Express (PCIe) 2.0 expansion slots, two x16 slots and two x4 slots. In the default configuration, one PCIe 2.0 x16 slot is occupied by the graphics card. Apple also reports that "all slots provide mechanical support for 16-lane cards" and there is a "300W combined maximum for all PCI Express slots." (75W*4)

And MacPro4,1 have 2 mini pcie 6 pin with 75W every cable.

The psu 980W output +12.2V - 79A.

The question is:

Every pcie x16 slot have a 75W max? :confused:
If i have 2 GTX 680 2GB connected... Are working with 225W or 150W per card? :confused:
 
camaluq said:
Every pcie x16 slot have a 75W max? :confused:
If i have 2 GTX 680 2GB connected... Are working with 225W or 150W per card? :confused:
Click to expand...

As far as I know, the max available power should be 225W for your card.

75W via the PCIe slot + 75W via the 6 pin cable 1 + 75W via the 6 pin cable 2
 
camaluq said:
The question is:

Every pcie x16 slot have a 75W max? :confused:
If i have 2 GTX 680 2GB connected... Are working with 225W or 150W per card? :confused:
Click to expand...
The answer is actually quite straightforward. 225W is available for one GPU card when using two 6-pin auxiliary power connectors plus the PCIe slot power, and 300W is available when two cards are installed (2x75W from the 6-pin connectors and 2x75W from the PCIe slots). BTW, it does not guarantee that each card would get the exact 150W only that 300W is available to both cards. Theoretically the internal PSU could provide much more than 300W, but there are no additional power connectors assigned for video cards.

There were some reports that the 6-pin power connector could draw up to 100W without any potential shutdown, but I'd not count on it and that's still not enough for two GTX 680's. If you want to install two cards for some intensive GPU computation, adding an external PSU is a much safer bet as shown in this thread.
 
butter use that money to buy one Flashing GTX 780 Graphic Cards :cool:

most powerful one can use without modified mac pro power supply .

need 10.9.2 to run
 
hendrix.to said:
butter use that money to buy one Flashing GTX 780 Graphic Cards :cool:

most powerful one can use without modified mac pro power supply .

need 10.9.2 to run
Click to expand...

I've thought about it for my MP 5.1, but I dislike the uncertainty when running something that could one day attempt to draw too much power. I know running something like FurMark for eight hours is an unrealistic load on any card, but it scares me that I could end up burning out my logic board and PSU.

I suppose if that happened my home insurance that covers 'accidental damage' could cover it though.
 
I had 2 cards connected to the logic board and gave Valley approx 2350 with hyperSLI in Bootcamp Windows 8.1.
When connecting a cable 6 pin each from sata dvd drives score was 2800 in hyperSLI in Bootcamp Windows 8.1.

I think this means that there really lack of power and YES is risky for the logic board.

Finally I decided to leave one card GTX680 which is the most reliable solution that works very well. Waiting for GTX880 - GM204 because is supposed to be a solution less energy requirements that GK110 but more performance that GTX680 and i think that OS X will have support quickly.

Look Gamescom 13/08/2014 - 17/08/2013.
 
camaluq said:
I had 2 cards connected to the logic board and gave Valley approx 2350 with hyperSLI in Bootcamp Windows 8.1.
When connecting a cable 6 pin each from sata dvd drives score was 2800 in hyperSLI in Bootcamp Windows 8.1.

I think this means that there really lack of power and YES is risky for the logic board.

Finally I decided to leave one card GTX680 which is the most reliable solution that works very well. Waiting for GTX880 - GM204 because is supposed to be a solution less energy requirements that GK110 but more performance that GTX680 and i think that OS X will have support quickly.

Look Gamescom 13/08/2014 - 17/08/2013.
Click to expand...

Currently HyperSLI is discontinued. The new one is calling Different Auto SLI.

Did you connect 2 gtx 680 with a splitter Y to aux pcie boost?

I'm using 2 680 with an 5.25" power supply 450watt.
 
No fsp x5 booster available now in spain. And yes i think that is the best way.

Works nvidia surround with different auto sli???

Don't undersrand what is pcie boost.
 
Last edited:
camaluq said:
No fsp x5 booster available now in spain. And yes i think that is the best way.

Works nvidia surround with different auto sli???

Don't undersrand what is pcie boost.
Click to expand...

PCIe Boost (The Connectors in The MainBoard for Powering the VGA)
 
2350 valley points: Two gtx680 with 4 pcie 6pin (2 from mobo with Y cables).

2800 valley points: Every gtx680 with 1 pcie 6 pin from mobo and one from superdrive power (2 yellow cables every pcie 6pin)
 
camaluq said:
I had 2 cards connected to the logic board and gave Valley approx 2350 with hyperSLI in Bootcamp Windows 8.1.
When connecting a cable 6 pin each from sata dvd drives score was 2800 in hyperSLI in Bootcamp Windows 8.1.

I think this means that there really lack of power and YES is risky for the logic board.

Finally I decided to leave one card GTX680 which is the most reliable solution that works very well. Waiting for GTX880 - GM204 because is supposed to be a solution less energy requirements that GK110 but more performance that GTX680 and i think that OS X will have support quickly.

Look Gamescom 13/08/2014 - 17/08/2013.
Click to expand...

did you gtx's flashed with mac bios?
 
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