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A word of caution before anyone tries this at home - this project is not the same as a retail product and none of the device connections are hot swappable . Meaning , if the devices are not attached properly or otherwise come loose during operation damage could occur to your Mac, the attached devices or both . Also , booster power to the GPU array must be active before the host computer is started up . Try this project at your own risk and enjoy the results when you do.
About a year ago, my flagship annual project involved installing and internally powering Dual GTX 970 Maxwell graphics cards for rendering purposes in a Nehalem Mac Pro . The benchmark results were respectable , especially with Cuda Core optimized applications .
This year's project involves connecting three even higher end Maxwell GPUs to another Nehalem Mac Pro , but they required external mounting for various reasons . The results are nothing less than stellar , easily surpassing last year's benchmarks and reinvigorating the usefulness of these older Macs . This is especially true since the material cost of the entire project does not exceed the cost of an empty Cubix expansion chassis (before any graphics cards are purchased) .
What this project involves is connecting three externally mounted non-EFI GTX 980 Ti video cards via heavily shielded PCIe cables to the host Mac Pro workstation's PCIe interface slots . Each card has a discrete cable and no splitting is used . An external Power Supply Unit with six eight pin VGA power connectors was necessary in order to provide booster power to each of the video card's two eight pin connectors . An open air frame / test bench (without a motherboard or any other component installed) was used to secure and properly position the GPUs . No additional fans were added to cool the GPUs at load, although adding them might prove useful . It doesn't take long for the cards' internal fans to spin up under load . Tests so far were brief - lasting less than 10 minutes in duration each .
Render tests were performed under OS X 10.10.5 Yosemite and 10.11.3 El Capitan . Results were basically identical .
Results :
LuxMark V 2.1 Sala (Open CL) = 10,798 .
Octane "Trench" Render Target PT (CUDA) = 24 seconds .
Blender BMW Blenchmark scene (CUDA) = 29.36 seconds .
System configuration :
Mac Pro 4,1 > 5,1 (factory 2009)
Factory internal 980 W PSU
2.8 GHz Six Core X5660 CPU
16 GB 1333 MHz memory (4 x 4GB)
250 GB SSD (Samsung 850 EVO) or 1 TB HDD (WD Blue)
DVD-RW drive
OS X 10.10.5 or 10.11.3
3 x EVGA GTX 980 Ti FTW video cards (@ $630 each) .
3 x 3M Twin Axial PCIe x16 500mm extension cable (@ $100 each) .
external 1000 W EVGA PSU (@ $160) .
DimasTech Test Bench Frame ($135) .
Total cost of array (not including host computer) is $2,485 , which is less than the cheapest brand new Cubix Chassis without any cards .
GTX 980 Ti cards were installed in the following slots :
Slot 1 (8 lanes electrical)
Slot 2 (16 lanes)
Slot 3 (4 lanes)
Optional GT 120 EFI UI card was occasionally installed in Slot 4 (4 lanes) .
An attempt was made to install a GTX 980 Ti card in each of the four Nehalem Mac Pro's PCIe slots via these cables . This attempt failed as the Mac refused to complete its POST . It simply went into a chronic loop trying to pass POST and did not crash , freeze or restart . There appears to be a firmware lock that limits these Macs to three Maxwell graphics cards , which would also explain why certain external expansion chassis have issues with recognizing additional installed graphics cards . It's not a chassis limitation, per se . It's a host computer limitation .
I have not performed a burn in stress test yet, as I only today found an utility (LuxMark v 3) to recognize multiple GPUs . Valley , Heaven and FurMark cannot stress test an array of cards in Mac OS X . I will provide thermal and stability data as I collect it . It might be necessary to provide additional cooling when the array is under load for an extended period .
Some additional last minute notes : rendering cards appear not to require more than 4 PCIe Rev 2 lanes each (electrical) , so the additional lanes provided by some of the slots are not necessary . This might prove useful with slot splitter cards in future configurations .
Questions are welcome .
I am Creation Machines .
![P2224505.JPG]( "P2224505.JPG")
![P2224506.JPG]( "P2224506.JPG")
![sala score JPEG.jpg]( "sala score JPEG.jpg")
![octane trench score JPEG.jpg]( "octane trench score JPEG.jpg")
![blender bmw score JPEG.jpg]( "blender bmw score JPEG.jpg")
![system profile GPU JPEG.jpg]( "system profile GPU JPEG.jpg")
A word of caution before anyone tries this at home - this project is not the same as a retail product and none of the device connections are hot swappable . Meaning , if the devices are not attached properly or otherwise come loose during operation damage could occur to your Mac, the attached devices or both . Also , booster power to the GPU array must be active before the host computer is started up . Try this project at your own risk and enjoy the results when you do.
About a year ago, my flagship annual project involved installing and internally powering Dual GTX 970 Maxwell graphics cards for rendering purposes in a Nehalem Mac Pro . The benchmark results were respectable , especially with Cuda Core optimized applications .
This year's project involves connecting three even higher end Maxwell GPUs to another Nehalem Mac Pro , but they required external mounting for various reasons . The results are nothing less than stellar , easily surpassing last year's benchmarks and reinvigorating the usefulness of these older Macs . This is especially true since the material cost of the entire project does not exceed the cost of an empty Cubix expansion chassis (before any graphics cards are purchased) .
What this project involves is connecting three externally mounted non-EFI GTX 980 Ti video cards via heavily shielded PCIe cables to the host Mac Pro workstation's PCIe interface slots . Each card has a discrete cable and no splitting is used . An external Power Supply Unit with six eight pin VGA power connectors was necessary in order to provide booster power to each of the video card's two eight pin connectors . An open air frame / test bench (without a motherboard or any other component installed) was used to secure and properly position the GPUs . No additional fans were added to cool the GPUs at load, although adding them might prove useful . It doesn't take long for the cards' internal fans to spin up under load . Tests so far were brief - lasting less than 10 minutes in duration each .
Render tests were performed under OS X 10.10.5 Yosemite and 10.11.3 El Capitan . Results were basically identical .
Results :
LuxMark V 2.1 Sala (Open CL) = 10,798 .
Octane "Trench" Render Target PT (CUDA) = 24 seconds .
Blender BMW Blenchmark scene (CUDA) = 29.36 seconds .
System configuration :
Mac Pro 4,1 > 5,1 (factory 2009)
Factory internal 980 W PSU
2.8 GHz Six Core X5660 CPU
16 GB 1333 MHz memory (4 x 4GB)
250 GB SSD (Samsung 850 EVO) or 1 TB HDD (WD Blue)
DVD-RW drive
OS X 10.10.5 or 10.11.3
3 x EVGA GTX 980 Ti FTW video cards (@ $630 each) .
3 x 3M Twin Axial PCIe x16 500mm extension cable (@ $100 each) .
external 1000 W EVGA PSU (@ $160) .
DimasTech Test Bench Frame ($135) .
Total cost of array (not including host computer) is $2,485 , which is less than the cheapest brand new Cubix Chassis without any cards .
GTX 980 Ti cards were installed in the following slots :
Slot 1 (8 lanes electrical)
Slot 2 (16 lanes)
Slot 3 (4 lanes)
Optional GT 120 EFI UI card was occasionally installed in Slot 4 (4 lanes) .
An attempt was made to install a GTX 980 Ti card in each of the four Nehalem Mac Pro's PCIe slots via these cables . This attempt failed as the Mac refused to complete its POST . It simply went into a chronic loop trying to pass POST and did not crash , freeze or restart . There appears to be a firmware lock that limits these Macs to three Maxwell graphics cards , which would also explain why certain external expansion chassis have issues with recognizing additional installed graphics cards . It's not a chassis limitation, per se . It's a host computer limitation .
I have not performed a burn in stress test yet, as I only today found an utility (LuxMark v 3) to recognize multiple GPUs . Valley , Heaven and FurMark cannot stress test an array of cards in Mac OS X . I will provide thermal and stability data as I collect it . It might be necessary to provide additional cooling when the array is under load for an extended period .
Some additional last minute notes : rendering cards appear not to require more than 4 PCIe Rev 2 lanes each (electrical) , so the additional lanes provided by some of the slots are not necessary . This might prove useful with slot splitter cards in future configurations .
Questions are welcome .
I am Creation Machines .
