MP 1,1-5,1 GTX 770 GPU upgrade on a 1,1 Mac Pro - what are the appropriate power cables?

[matan2001]

Hi there, Recently I was given for free an old Mac Pro 1,1 that has a 2 x 2.66GHz Dual Core Intel Xeon, 13GB of RAM, and an NVIDIA GeForce 7300 GT.

I thought this would be a good starting point for a basic secondary computer but I wanted to upgrade it from 10.7 to the latest compatible version of macOS - 10.11 El Capitan.

I understood that in order to update to 10.11 - you need to upgrade the stock GPU (mine has 256MB of VRAM) to a GPU that has 512MB VRAM minimum.

My brother just upgraded his PC's GPU and didn't need his GTX 770 (Gigabyte GV-N770OC-4GD) anymore and so I wanted to use it in this Mac Pro but I couldn't quite understand how to go about with the upgrade.

Using advice from a Reddit post I made a few weeks ago, I updated macOS to 10.11 without any problems and I would like now to go ahead with the GPU upgrade.

The problem is I encountered quite a few conflicting sources about which power cables to use between the GPU and the Mac itself.

One person says to use one 6-pin to 8-pin and one 6-pin to 6-pin cable.

Another says to use one 6-pin to 6-pin cable, and one 6-pin to 6-pin cable connected to a female 6-pin to male 8-pin adapter.

And another said to use a 6-pin Y adapter in a blog post which confused me even more TBH.

I might just be overthinking this and it may not matter much but since I'm dealing with power consumption i thought it would be best to be on the safe side.

I'd appreciate if someone who knows what the correct cables are could shed some light on this matter

 

[TzunamiOSX]

I had installed a Titan X with 250 Watt (6+8) inside my 3,1. The Titan X need around 25 Watt more than the 3,1 support. This was no problem inside my 5,1 (with EVGA Powerlink to balance), but inside my 3,1 I will get shutdowns really often. I would say, a better solution is a GPU with dual 6-Pin.

The safest way is 2x6-Pin —> 8-Pin, 8-Pin —> 1x6-Pin and 1x6-Pin (Or an EVGA Poverlink).

 

[Dayo]

Titan X with EVGA Powerlink was no problem in my MP51 but I often get shutdowns on my MP31.

Is that with the Powerlink still present?

 

[TzunamiOSX]

Is that with the Powerlink still present?

In German it is available. Search for "EVGA Powerlink" in Google

Or do you mean the System 5,1 with the Titan X? No the 5,1 now has a Vega Frontier and the Pixlas Mod.

https://forums.macrumors.com/threads/pixlas-4-1-mac-pro-mod.1859652/post-31055747

 

[Dayo]

"EVGA Powerlink"

I wanted to confirm whether the powerlink was also connected to the Titan X when you got the shutdowns on the MP31.

That is, did the powerlink only prevent shutdowns on MP51 but not MP31?
Whether the powerlink was also used with the Titan X on the MP31 was not clear.

 

[TzunamiOSX]

Ah ok

The Powerlink distributes the load evenly, but the load is still above the specified values.

The 5,1 can with up to 120? Watts before emergency shutdown, perhaps the 3,1 doesn’t allow the same.
The 3,1 with the Powerlink also shut down on boot. I think there are short peaks on boot. After 3 shutdowns I have reinstalled my 980 GTX with 2x6-Pin connectors to my 3,1.