Macpro, mid 2012 multiple graphics cards conflict..

Question

Macpro, mid 2012 multiple graphics cards conflict..

Beefing up my GPU CAPABILITIES on my mid 2012 Macpro has become a priority for me. In my real job, I use Photoshop to earn a living and the two ATI 1GB 5770 cards that I purchased with the machine work beautifully for that purpose. However, when I ran my X-plane flight simulator, a one gig GPU didn't give me the kinds of frame rates that I am looking for (X-Plane is not optimized to take advantage of the duel cards).

So based on my reading, I decided on adding a 6 GB Nvidia 980ti to the first X16 PCIe slot (used, from EBay for around $400). In the second X16 slot my plan was to try and run one of the original ATI 5770 cards. Not unexpectedly, here is where the conflict is.

I am running Sierra and Nvidia provides software on its website. So the 980ti runs beautifully by itself and I can either power the middle screen or the middle screen and the two outboard screens as well (I run three monitors ).

I would prefer to run my center screen off the 6GB card only, and insert one of my ATI 5770s and run the two outboard monitors off of that since I don't use those monitors to run the simulator. Except my computer won't power on if both the Nvidia as well as the ATI card are installed in their respective PCI slots. In my reading I've also learned that my Mac Pro does not like that there are cards from two different companies in the same machine even though the software for both exists there. There is plenty of information on how I can power the two cards but I can't get past the fact that the machine won't boot with both cards in place. Although I did read on one of the threads here that someone has achieve this by disconnecting the two outboard monitors during rebooting and then connecting them after boot. But then on restart the conflicts reemerge and the connecting – reconnecting ordeal must be gone through again.

Anyone have any ideas/similar experiences???

Mac Pro, iOS 10.2, MID-2012

Posted on Jan 17, 2017 10:33 AM

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Answer 1

Jan 17, 2017 5:27 PM in response to FlyingFortress

You must provide appropriate power for all the cards in your machine, or it will not boot up properly. This is not a theoretical discussion. So you need to solve the power problem FIRST, before you can make further progress using two cards.

As for mixing Vendors, that should not be an issue, or can be worked around.

You could also consider using a GT 120 as the second card, as it does not require ANY Aux power.

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Answer 2

Jan 17, 2017 5:51 PM in response to Grant Bennet-Alder

Thanks so much Grant. You may be right. I really studied the power consumption issues of both the 980ti as well as the those of the ATI 5770 before the fact. The 2012 Macpro is a 500W machine with apparently 300W allotted to all the PCIe slots. I saw this upgrade done on Youtube with a 980ti AND an ATI 5880. For the 980ti, he used both card 6-pin power outlets on the mother board, via an adapter, to one 8-pin connector on the GPU. For the 6-pin connecter on that 980, he tapped a SATA outlet from and empty drive bay with a SATA-to-6 pin connector. For the ATI 5770 I had tapped another empty drive bay with another SATA to 6-pin adapter which plugs into a single 6-pin. It was my understanding that the video cards began pulling extra power as they were loading up. If I'm wrong—there'a always a first time ;-)—then what's the next step on adding more power, specifically? I had also read that a guy had tapped power directly from the 12V outlet in the PSU. What do you think my next step should be? I won't hold you responsable. Thanks

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Answer 3

Jan 17, 2017 6:29 PM in response to FlyingFortress

If you think you have already solved the power problem, the ultimate litmus test will be when you ask both cards to work hard. If you over-draw the power supply, it will do a sudden power-off.

won't power up may only be lingering software problem. I seem to remember there were problems with certain versions and multiple display cards or mixed vendors on two cards, but I though they were resolved in a later version. What version of macOS are you running.

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Answer 4

Jan 17, 2017 6:49 PM in response to Grant Bennet-Alder

Ok, thanks. I upgraded to the newest version of Sierra because I read that Nvidia had written the drivers for the 980ti so this PC card would give me a boot screen, not required, but nice. But the more I think about what you're saying, the more this looks like the machine "knows" it shouldn't try to power up if the PSU is compromised, like the PCI bus demanding too much power. I could buy an external aux PSU, hook it up and see if it all works. If it doesn't, I could return the aux PSU....? On your other comment, yes, I HAVE read that running cards from 2 different companies on this MAC will "send the machine into Kernel Panic." But yes, either card works perfectly alone, but they don't work together. What I really need to do again is go to all the specs and compare the real PSU output, the power the cards need to draw and verify that I'm tapping the card power from the right outlets. I'll do that tomorrow. Thanks, very stimulating.

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