I want to add a GTX 980 ti as a second GPU on a Mac Pro 2012 12-core. Do I have to add an external PSU to power it?
Mac Pro, OS X Yosemite (10.10.5)
No. For details see http://www.macvidcards.com/store/p49/Nvidia_GTX_980_Ti_6_GB.html
Thanks, Allan. But the link does not specify about it being a second GPU. The Radeon 5770 also draws some amount of power. I am a bit concerned about that.
Why as a second GPU? is four ports not enough?
I am a colorist working on Davinci Resolve. This software uses one GPU to draw the program interface and any remaining GPUs to process the video editing. Yes, it is that consuming. Depending on the project, people use up to four extra GPUs to process everything.
You can install two 5770s without external power. Each requires only one aux power cord.
But do not attach any displays to the second card -- that defeats the idea of Un-interrupted GPU processing.
It does make me wonder whether you would rather have two Nvidia cards. How about a GT120 (no aux cable) as the primary and the 980 as your GPU processor?
That would be a good setup. However, that would require me to buy the gt120 (which only has 512MB opposite the 1GB 5770) and remove the already contained 5770.
My main concern would not be that lack of cables, but the power draw. I am afraid maybe the Mac Pro would not generate power enough to both cards and fry something in there. I am finding it kinda hard to get an exact information on the web.
You can get an aftermarket GT120 that has 1GB. It is still not much of a display card, but you want the GTX 980 to do the real Heavy Lifting.
You can sell your working Apple 5770 for over US$100, maybe as much as twice that.
And what about a newer GT 630? It has 2GB and is pretty cheap too.
I don't know, but I expect other Readers do.
The Mac Pro provides power to video cards via the PCIe slot itself and one or two 6-pin PCIe auxiliary power leads. The PCIe slot itself provides 75W, each 6-pin cable officially provides 75w making a maximum total possible of 210W.
As there are only two sockets on the Mac Pro logic board for auxiliary power this means you can either use one video card with 75+75+75 or two video cards with 75+75 and 75+75. Since the video card you want to use requires two 6-pin auxiliary power leads as well as the PCIe slot power officially you would not be able to have a second video card. Therefore the answer is yes if you want to use the GTX 980ti and a second video card you should use an additional external power supply.
For what its worth an 8-pin auxiliary PCIe power connection would provide 150W but the Mac Pro does not have such connections. Some people have successfully drawn more than the official 75W per 6-pin connection on the Mac Pro logic board by using a 6-pin to 8-pin adapter but the danger is that over time this may burn out the logic board.
PS. Some people fit a second additional power supply internally into the optical drive bay of the Mac Pro but still having the power lead run outside the Mac Pro via an empty PCIe slot.
Thanks, John. And if I just replace the 5770 for the GTX 980ti, do I need to be concerned about power? I intend on using a 6-pin to 8-pin adapter without any other cards, just the GTX.
Marginal at best, Per
http://www.geforce.com/hardware/desktop-gpus/geforce-gtx-980-ti/specifications
the card requires 250 watts
The PCle slot supplies 75 W and each AUX is also 75 W for total of 225 W.
Apparently (I don't have this card myself), the GTX 980ti has a 6-pin and an 8-pin power socket and therefore officially would require a computer to have the same connectors to provide the required amount of power. Remember an 8-pin cable can provide twice the power of a 6-pin cable.
As previously discussed a Mac Pro only has two 6pin connectors so on that basis it is impossible to properly use a 6-pin and an 8-pin cable with a Mac Pro. In reality the amount of power this card needs at 250W is only very slightly more than the 75+75+75 = 225W a Mac Pro officially provides. Again in reality this card would only need the full 250W if it was being pushed to the absolute maximum workload which most of the time would not be the case. So yes, if you have this card and don't have a 5770 fitted then your fine with a 6-pin to 6-pin cable plus a 6-pin to 8-pin cable.
Note: You could still have a GT 120 fitted at the same time as the GTX 980ti.
Note: Most but not all video cards with an 8-pin socket are designed so that a 6-pin plug will fit in the 8-pin socket.
I want to add a GTX 980 ti as a second GPU on a Mac Pro 2012 12-core. Do I have to add an external PSU to power it?
