MP 1,1-5,1 GPU (GTX780 3GB) issue

[Superberto92]

Hello everybody!!
I decided to upgrade my mac pro 3.1 with a new GPU (GTX 780 3gb Gygabyte version) the ebay seller sold it as "flashed for mac"
I have installed 10.14.6 (18G103) with dosdude1 patch.
The GPU is conected with a PCIe 2x6 pin to 8 adapter on slot 1, and the system recognize it.
I updated with the latest CUDA available.

When I try to start the mac connecting the screen on the new GPU the system does not boot (i can see the screen with apple logo and loading bar stuck at half),if i connect the screen to the old card everything is working fine.
Does anyone have some suggestion on how to solve the problem?
Thanks!

 

[KeesMacPro]

Running Mojave with an AMD and a Nvidia installed causes issues/ doesnt work.
Did you test with the GTX770 installed and the HD2600 removed?

 

[Superberto92]

Thanks for the feedback, I just tried to remove the AMD and leave only the GTX but the result is still the same.

 

[KeesMacPro]

The GTX780 is a Kepler card , which is supported natively in Mojave.
There are no Nvidia web drivers for Mojave, but that isnt necessary either to work.
I dont know what CUDA driver you installed, and TBH didnt know there were CUDA drivers for Mojave , probably uninstalling the CUDA driver solves it.

AFAIK all driver support stopped at 10.13.6 (High Sierra)

After uninstalling the CUDA driver , restart and do a triple NVRAM reset.

 

[Superberto92]

Ok, deleted all the file and did multiple NVRAM reset, there is still the same problem...
Maybe I can try to run an older OS version?

 

[KeesMacPro]

Yes, try an unpatched OS .
The card is supported from 10.8.3 and later.

Are you sure you connected the power cables correctly?

There should go 2 cables from the MainBoard to the GPU:
1 mini 6pin > 8 pin cable and
1 mini 6pin > 6 pin cable.

Assuming the GPU has a 8pin+ 6pin power connector.

 

[Superberto92]

The card has 2 8pin connector, only one is connected with a Y cable to both of the mac 6pin connector, the other one is empty.

I will try to run OS X 10.11

 

[KeesMacPro]

The card has 2 8pin connector, only one is connected with a Y cable to both of the mac 6pin connector, the other one is empty.

Both GPU connectors must be connected, best case= not working , worst case= damage to the card !

I'd first connect them correctly with 2 cables mini6pin> 8pin.

 

[Superberto92]

Thanks a lot for the precious advice.
I will buy the single 6 to 8 pin and try again, with the right connection😀

 

[KeesMacPro]

In boca lupo