MP 1,1-5,1 Second GPU with Mac Pro 4.1 / 5.1 (RTX 3070)

[Aryan-x86]

Hi there,

I have a Mac Pro 4.1, flashed to a 5.1, running Windows 10 only through Bootcamp.

I am currently using a MVC Flashed MSI GTX 970, with boot screen and I upgraded my other PC's GPU today, and I have a leftover RTX 3070 that I plan on using for a new build later this year.

Now I'm wondering if it's possible to use the RTX 3070 alongside the GTX 970 temporarily and keep my Boot screen? I believe I am powering the GTX 970 with some kind of adapter? Not with the Pixla Mod thing.

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Can/Should I power the RTX 3070 with an external PSU?

Will Windows 10 work?

Will MacOS (on another SSD) work?

Will I keep the boot screen?

Is it better to use the RTX 3070 only, if I'm only gonna use Windows, thus getting rid of the boot screen?

 

[tsialex]

MacPro firmware does not have UEFI HII support, NVIDIA cards since the RTX 2xxx require HII and won't complete POST with a MacPro5,1.

 

[RyGuyver]

MacPro firmware does not have UEFI HII support, NVIDIA cards since the RTX 2xxx require HII and won't complete POST with a MacPro5,1.

Is it just the boot/POST process that is the issue, or will the 3000 series and higher cards flat out just not work with these old 5,1 Macs running Windows 10 even in a dual-GPU type configuration?

If, for example, I have something like a very low power GeForce GT 710 in Slot 1 with a RTX 3070 in Slot 2, is that enough to make it through boot where the RTX 3070 can then be utilized for certain applications such as gaming?

 

[tsialex]

Is it just the boot/POST process that is the issue, or will the 3000 series and higher cards flat out just not work with these old 5,1 Macs running Windows 10 even in a dual-GPU type configuration?

If, for example, I have something like a very low power GeForce GT 710 in Slot 1 with a RTX 3070 in Slot 2, is that enough to make it through boot where the RTX 3070 can then be utilized for certain applications such as gaming?

Like I wrote, the issue is that NVIDIA with the RTX 3xxx GPUs started to require UEFI v2.3.1c HII support, since Mac Pro is still EFI 1.10 and does not support HII, you can't even complete POST with a RTX 3xxx installed. So, you power on to nothing but beeps when a RTX 3xxx/4xxx is installed in a MacPro5,1.

Said that, seems that some 3rd party NVIDIA GPUs have a non-standard factory firmware that have a workaround for the missing HII support and can boot with a MacPro5,1 instead of just crashing at POST, at least two people here got it working with 144.0.0.0.0 + EnableGop.

The problem is that any NVIDIA GPU that have the reference firmware won't work. Finding the right GPU that works is the problem.