MP 1,1-5,1 Losing my sanity trying to install nVidia GPU in MP3,1

[zucc4prez]

Hi all, I purchased a 770 GTX and have been trying to make it work in my Mac Pro 3,1 (which came stock with an ATI Radeon HD 2600 XT) for the best part of last week. I am running Mojave but the 770 GTX is one of the Kepler cards so even if I can't install the web drivers they should be pre-loaded. Unfortunately, I have had no success. These are the different configurations I've tried to no avail:

• Installing the 770 GTX in the first GPU port (16x), no other card installed. GPU lights up and fans spin quicker than a nuclear reactor but no video ever, even after waiting for a long time.
• Same setting as before but including the other AMD card it came with alongside the 770 in one of the non-16x ports. I get video only coming from the AMD card, other card does not even appear under "System report" but lights up and fans spin.
• Putting the AMD card in the 16x port and the nVidia in the non-16x port. GPU lights up but fans are silent. I get video from the AMD card but not the nVidia card, but the GTX is detected under "System report".
• Using the nVidia card alone in the non-16x port. No luck here either.

The 770 comes with a 6-pin port and an 8-pin port. I have tried all the previous configurations with:

• Both ports connected, each hooked up to each of the mini pcie ports in the motherboard.
• Joining the output of both mini pcie ports using a Y adapter to 8-pin pcie, leaving the card's 6-pin input alone.

but alas, it made no difference whatsoever. I have ran out of Google searches and 2008 Youtube videos and am on the brink of losing my sanity with this GPU. Can anyone give me some much appreciated advice? Thank you for at least reading.

 

[tsialex]

You can't mix match GPUs after High Sierra, with Mojave you have to use AMD or NVIDIA.

Did you tested the GTX 770 with a PC to make sure it's working?

 

[zucc4prez]

You can't mix match GPUs after High Sierra, with Mojave you have to use AMD or NVIDIA.

Did you tested the GTX 770 with a PC to make sure it's working?

Haven't had the opportunity to test it, but given it's detected sometimes and lights up and fans spin I'm not sure that it being broken is the issue. I also tried resetting SMC and PRAM everytime but that did nothing either, it's so strange. Is something else needed software-wise that I'm missing?

 

[tsialex]

Haven't had the opportunity to test it, but given it's detected sometimes and lights up and fans spin I'm not sure that it being broken is the issue. I also tried resetting SMC and PRAM everytime but that did nothing either, it's so strange. Is something else needed software-wise that I'm missing?

Install ElCapitan to a spare HDD and test it there, this way you can be sure if is a hardware or software problem.

 

[Macschrauber]

Btw you must feed all pcie power connectors

 

[startergo]

Not only all power connectors but enough power i.e. 150W on the 8 pin and 75W min on the 6 pin. So the safest way is a PSU mod and less safe using the 2 SATA to 6 pin converter in which case you should only test the card. Don't leave it permanently like this and run heavy load on the card constantly.

 

[Macschrauber]

In the real world on a 6 and 8 pin card it is imho enough to use a 2xmini 6 pin to 8 pin.

Then single 8 pin to 2x 6plus2

Both pcie ports deliver 100 watt, this and the load balancing should give a stable situation (if one does not run Furmark 24/7 )