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Dual GPU's in 2010 Mac Pro

L

Lauwie

macrumors regular
Original poster
Jun 17, 2011
129
38
A friend gave me GTX 570 and I'dd like to use it in my Mac Pro alongside my R9 280X.

I'm just really puzzled as to how I need to supply the 570 with power.
I've come across this thread: https://discussions.apple.com/thread/4509919 and it says I need to use a molex to PCIe power cable but I can't find a molex connector on my motherboard ?
 
No, you don't have enough power from existing connectors in your computer to power both cards.

The second video card will require an additional power supply, either external or one designed to mount in the optical bay. Alternatively, you can try your hand at wiring directly from the existing power supply to the card as described here.
 
ActionableMango said:
No, you don't have enough power from existing connectors in your computer to power both cards.

The second video card will require an additional power supply, either external or one designed to mount in the optical bay. Alternatively, you can try your hand at wiring directly from the existing power supply to the card as described here.
Click to expand...
And what about using the SATA power ?
 
Lauwie said:
A friend gave me GTX 570 and I'dd like to use it in my Mac Pro alongside my R9 280X.

I'm just really puzzled as to how I need to supply the 570 with power.
I've come across this thread: https://discussions.apple.com/thread/4509919 and it says I need to use a molex to PCIe power cable but I can't find a molex connector on my motherboard ?
Click to expand...
450W PSUs that fit in optical drive bay can be found for $25-75. Use to be easy to find one for $30-40 on Newegg. Offers 2 x 8-pin and 2 x 6-pin outputs. Connecting it up so that it will get power when the Mac is powered. The cabling can be the hard - and messy - part.
 
IowaLynn said:
450W PSUs that fit in optical drive bay can be found for $25-75. Use to be easy to find one for $30-40 on Newegg. Offers 2 x 8-pin and 2 x 6-pin outputs. Connecting it up so that it will get power when the Mac is powered. The cabling can be the hard - and messy - part.
Click to expand...
Can you send me a link ?
I don't have newegg in Belgium but I can look up the parts :)

Random thing: the guys over at "create pro" told me they're working on a mod for that will allow Dual GPUs and doesn't require electric modification, they told me it should be ready soon. If this is true I'm quite excited that they've found a way to do it that doesn't require electric modification :)
 
Actually you can use SATA ports for powering dual cards. Load isn't distributed evenly, especially when one of GPU power connectors is 8-pin one.
My customer was running dual 280X setup in his 2009 with both 8-pin plugs connected to AUX connectors and 6-pin ones to SATA ports. It worked flawlessy for few 24h renders in Resolve until he wanted to use SATA ports back, so I modded the PSU.

Dual 7970s worked the same way in 2008, however there was performance drop when running Luxmark CPU + GPU benchmarks. But 2008 has different PSU rails setup than 2009/10, so this was the issue most likely.

Regarding CP "trick" it's called undervolting. With some clocks offset it will allow to lower power demand of the card with minimum computing power loss. But it does have its limitations, so I doubt that one could run 2 undervolted Titans (for example) without electrical modifications of the MP.
 
666sheep said:
Actually you can use SATA ports for powering dual cards. Load isn't distributed evenly, especially when one of GPU power connectors is 8-pin one.
My customer was running dual 280X setup in his 2009 with both 8-pin plugs connected to AUX connectors and 6-pin ones to SATA ports. It worked flawlessy for few 24h renders in Resolve until he wanted to use SATA ports back, so I modded the PSU.

Dual 7970s worked the same way in 2008, however there was performance drop when running Luxmark CPU + GPU benchmarks. But 2008 has different PSU rails setup than 2009/10, so this was the issue most likely.

Regarding CP "trick" it's called undervolting. With some clocks offset it will allow to lower power demand of the card with minimum computing power loss. But it does have its limitations, so I doubt that one could run 2 undervolted Titans (for example) without electrical modifications of the MP.
Click to expand...
Yeah they did explain that, that's why they offer dual 280Xs.
Though they're working on some mod that works for all GPUs.
Would you be willing to mod my PSU ?
 
If you need multi-monitor config there are 120GT cards for that. If you need power there is 980Ti. Why put 2 cards?

I have got TitanX recently and it is awesome :) Have 5870 & 120GT sitting in a drawer :)
 
VikNomad said:
If you need multi-monitor config there are 120GT cards for that. If you need power there is 980Ti. Why put 2 cards?

I have got TitanX recently and it is awesome :) Have 5870 & 120GT sitting in a drawer :)
Click to expand...
Well I'm a student and not swimming in cash :p
I still have to buy a rMBP for september (gonna study Computer Science in TU Delft).
I like my AMD card for gaming and Apps that use OpenCL (it's also pretty good when you want to use brute force hacking), but I also use blender quite often and they failed to bring the OpenCL kernel to OS X so thats why I look forward to using the 570 in my system :)
 
VikNomad said:
If you need multi-monitor config there are 120GT cards for that. If you need power there is 980Ti. Why put 2 cards?

I have got TitanX recently and it is awesome :) Have 5870 & 120GT sitting in a drawer :)
Click to expand...

I would like to give OSX and Windows their own card each instead of two. This is possible in Windows to disable any device in Device Manager. In OSX if I try to boot with two cards and don't have a driver for both it goes into an endless boot cycle
 
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SoyCapitanSoyCapitan said:
I would like to give OSX and Windows their own card each instead of two. This is possible in Windows to disable any device in Device Manager. In OSX if I try to boot with two cards and don't have a driver for both it goes into an endless boot cycle
Click to expand...
If you have the Nvidia drivers installed in OS X this shouldn't be a problem ?
 
Lauwie said:
If you have the Nvidia drivers installed in OS X this shouldn't be a problem ?
Click to expand...
What if Nvidia drivers suddenly stop being developed? Then you can't update the OS anymore. That's why I think we should be prepared for the solution. The best I can think of is to have my newer card working only in Windows and the older Apple card only for OSX.
 
SoyCapitanSoyCapitan said:
What if Nvidia drivers suddenly stop being developed? Then you can't update the OS anymore. That's why I think we should be prepared for the solution. The best I can think of is to have my newer card working only in Windows and the older Apple card only for OSX.
Click to expand...
Don't think thats gonna happen any time soon, as long as people continue to use Mackintosh and cMPs the user base would be big enough to put the effort in developing OS X drivers.
I don't know for sure but normally the code base between the Linux and Mac drivers should be pretty similar.
And don't forget there will defo be macs with Nvidia GPUs in the future
 
Lauwie said:
Don't think thats gonna happen any time soon, as long as people continue to use Mackintosh and cMPs the user base would be big enough to put the effort in developing OS X drivers.
I don't know for sure but normally the code base between the Linux and Mac drivers should be pretty similar.
And don't forget there will defo be macs with Nvidia GPUs in the future
Click to expand...
I try to be equally hopeful but also be prepared with alternative options
 
Lauwie said:
Can you send me a link ?
I don't have newegg in Belgium but I can look up the parts :)

Random thing: the guys over at "create pro" told me they're working on a mod for that will allow Dual GPUs and doesn't require electric modification, they told me it should be ready soon. If this is true I'm quite excited that they've found a way to do it that doesn't require electric modification :)
Click to expand...


Do you want Pretty or functional? If you can't find a Pretty Optical Bay Power Supply ... Hide you a Beast of a Powersupply down behind your Pro and put some sleaves over the cables and feed them through an empty slot on the back. This method alows to to buy a 1600 watt monster ... pull both of those cards you have and feed 2 7990's :) or just about anything your heart desires ...LOL
[doublepost=1454940088][/doublepost]
Lauwie said:
Well I'm a student and not swimming in cash :p
I still have to buy a rMBP for september (gonna study Computer Science in TU Delft).
I like my AMD card for gaming and Apps that use OpenCL (it's also pretty good when you want to use brute force hacking), but I also use blender quite often and they failed to bring the OpenCL kernel to OS X so thats why I look forward to using the 570 in my system :)
Click to expand...


I have a solution for you ... No cost even ..... Plan you week out better. Swap out your cards for whichever night/day it's gonna be. 570 for your Blender sessions and put the awesome little 280x back in when you start thinking about wanting to go to Jail or worse getting killed with your little Hacking Hobbie. "Brute Force" takes on a whole new meaning when you land in the Pen .... LOL Your new buddies there will be more than happy to explain it to you.
 
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