Mac Pro 3,1 PCI Power Splitter

honeycombz

macrumors 6502
Original poster
Jul 6, 2013
454
108
Hey, I'm planning on installing a GTX 680 into my 3,1. It runs on 2 power cables and I think I've got one of the two power ports in use at the moment and am wondering if it is ok to run both the power cables through a splitter to one of the ports?
 

jeeplj8

macrumors member
Jan 4, 2014
48
3
I would guess that depends on what is already drawing juice? Most people report they are fine until they try to run dual cards.

Oh, and my GTX 970 is dual port, and I am running it off a splitter, but not drawing any other power.
 

honeycombz

macrumors 6502
Original poster
Jul 6, 2013
454
108
I'm currently running 1 GPU the 5770 which I would be replacing, the Apricorn Velocity Solo x1, 3 HD spinners and 2 SSDs. That's it. So I definitely wouldn't be running 2 GPUs so do you think I'm fine? Also, can I use any old splitter or is there a specific one I need to get. 6 pin, 8pin... not really sure.
 

TzunamiOSX

macrumors 6502
Oct 4, 2009
301
46
Germany
Hey, I'm planning on installing a GTX 680 into my 3,1. It runs on 2 power cables and I think I've got one of the two power ports in use at the moment and am wondering if it is ok to run both the power cables through a splitter to one of the ports?
Not possible, because the 3,1 has 5 separate 12V rails. The power ports are limited to an absolutely max of around 100 Watt (emergency shutdown), but you need 150 Watt for the 2 ports of the 680.
 
Last edited:

honeycombz

macrumors 6502
Original poster
Jul 6, 2013
454
108
Ok, so I need to have one power cable going into one port. I'll see about routing the power to whatever is there in one of the ports already somewhere else as it probably doesn’t need as much as the GPU. Maybe I can split the power off of the optical drive.
 

TzunamiOSX

macrumors 6502
Oct 4, 2009
301
46
Germany
Maximum of one sata power connector is 4,5 Ampere. A 6-Pin GPU power connector supports up to 6,25 Ampere.

You need an Y cable for a save gpu use, but there is also the rail problem. Which rail is for what part of the board? Perhaps there is not enough power for a GPU on the drive connectors.

Why don't use the 680 standing alone? In a 3,1 it is dangerous to get more power than allowed. The 5,1 has a single 12V rail and this gives more options.
 
Last edited:

jeeplj8

macrumors member
Jan 4, 2014
48
3
I'm currently running 1 GPU the 5770 which I would be replacing, the Apricorn Velocity Solo x1, 3 HD spinners and 2 SSDs. That's it. So I definitely wouldn't be running 2 GPUs so do you think I'm fine? Also, can I use any old splitter or is there a specific one I need to get. 6 pin, 8pin... not really sure.
I ran a 650Ti in my 3.1. Note that it had a single 6 pin power port. I used an 8 pin to 6 pin converter (and an extension because the power port was too far away.)
 

honeycombz

macrumors 6502
Original poster
Jul 6, 2013
454
108
Just to doublecheck does anyone know/suggest a comparable GPU that would only require one PCIe slot on the off chance I run into problems? The only other slot I use is for the Apricorn Velocity Solo X1 and I'm concerned if that is not in one of the top 1 or 2 slots I might run into issues. Not positive on that just wanted to doublecheck about GPU alternatives that may be less of a headache.
 

honeycombz

macrumors 6502
Original poster
Jul 6, 2013
454
108
Just bought an MSI Lightning Nvidia GTX 680 2GB flashed for Mac for a decent price plus 5% ebates and the power cords. Fingers crossed.
 

TzunamiOSX

macrumors 6502
Oct 4, 2009
301
46
Germany
Every GTX 680 needs 2 6-pin connectors. The 680 OC needs up to 2 8-pin connectors.

If you need a single slot, single 6-Pin card, use a Quadro 4000 Mac Edition.
 
Last edited:

honeycombz

macrumors 6502
Original poster
Jul 6, 2013
454
108
Ok thanks. I'll keep that in mind. Hoping the 680 pans out would way better than the 5770.
 

ActionableMango

macrumors G3
Sep 21, 2010
9,267
6,253
Hey, I'm planning on installing a GTX 680 into my 3,1. It runs on 2 power cables and I think I've got one of the two power ports in use at the moment
I'm currently running 1 GPU the 5770 which I would be replacing
I'm confused. What is the splitter for? The 5770 uses one of the two power ports, but you are removing it so you will have both power ports free for the 680.
 

honeycombz

macrumors 6502
Original poster
Jul 6, 2013
454
108
Hey, I got the new card installed. Wondering if I need to update drivers or anything? Seems the CUDA driver is outdated? Please see attached. (Disregard the monitor, it is old, getting a new one). Also, should I care that my Apricorn Velocity Solo x1 sits directly above this card? There is small space between the two... I guess the heat gets sucked out the back of the machine.
gpu.png
 

honeycombz

macrumors 6502
Original poster
Jul 6, 2013
454
108
I think in system report > extensions > geforce the version is 10.10.4. If that means anything.
 

honeycombz

macrumors 6502
Original poster
Jul 6, 2013
454
108
Ok, I installed Cuda 8.0.81 and NVIDIA Web Driver 346.03.15f07. Things seem to be running pretty smooth, I like this card. Why does InDesign not allow you to use GPU Performance unless you are hooked up to HIDPI monitor? Seems odd since the other CC apps don’t have that requirement. Strange.