Disabling unused stubborn GPU

[oxox]

Hello everyone,

 

I have a multiboot install, all on separate SSD via hotswap. It's basically everything Windows from XP to 11, Linux and.... Snow Leopard on OpenCore 0.71.

Base is a I7 4770 on a Asus B85 plus. I have everything running on AHCI and all OS can use the same Bios settings. What means i can simply swap hard drives when i want to run Leopard or XP or whatever. Fire and forget.

 

So i got a GTX Titan in PCIe Slot 1 and a Quadro 4000 in PCIe Slot 2. The Quadro is dedicated to Snow Leopard only. The Titan does the main job, providing all the other OS with decent computing power for my needs. 

 

Everything is running fine, even SL is happy. With one exception: When the Titan is around, it will use the Titan for booting and not the Quadro.

When i unplug the monitor cable from the Titan it will boot into a black screen.

 

So i used the disable-gpu option in the config.plist ->nope... 

Then i carefully made a SSDT for disabling the PCIe Slot 1 -> nope...

In short: it will act as if i did nothing to disable it. It happily boots into SL in 1024x1024, disrespecting available kexts for the Quadro.

 

Interesting thing is that when i pair the Titan with a Radeon HD 5770, the unsupported Titan will boot, but the Radeon will use the native Snow Leopard kexts and work with acceleration etc... So basically i will boot into a dual monitor setup, which is usable for me because i use only one monitor with switchable inputs. So i can use the side with the accelerated desktop.

Thing is the Radeon is a dual slot card and the Quadro is a single slot card. And the Radeon blocks a PCI slot i need. Hence the Quadro. I drove 90kms for it today to run into this little disappointment.

 

So can i conclude my Motherboard will only boot from PCIe slot 1 no matter what i do? And my only solution is to put the more powerful GPU from the 16x slot to the 4x slot and the Quadro vice versa?

 

Does anyone of you know another hack that could sail me around this cliff?

Edited April 22, 2025 by oxox
Typo

[oxox]

So after a deep dive into graphics cards and UEFI roms, the particularities of Snow Leopard and the Quadro 4000... I can tell that it just won't work smacking two Nvidia GPUs in the same box as Snow Leopard, especially when the GPU in the first PCIe slot is unsupported.

I tried everything. I flashed the Quadro 4000 from PC Bios to Apple UEFI etc... Won't work.

What will work though is an unsupported Nvidia card in combination with a supported ATI card. But you can't disable the GPU in the first slot. Not with a SSDT and not via config.plist disable-gpu entry. And especially not when you need to rely on CSM, because then You can't use whatevergreen.

 

So this thread is [solved]

Edited April 25, 2025 by oxox
typo