Suggestions for AMD GPU for triple boot (Win 10 + Manjaro + Big Sur), currently have 1080ti

TLDR - Want to run a 1080ti + AMD GPU setup for BigSur/Catalina; possible? Please suggest GPU!

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Hi, I have been wanting to do a triple boot setup (OpenCore) for a while now. Watched many videos and forums and somehow missed the fact that my 1080ti won't be supported.

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Windows for office work + gaming, Linux for Deep Learning (hence the Nvidia GPU), trying out MacOS cause why not. Would want to shift to MacOS completely for my coding needs (need latest XCode and hence BigSur).

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Below are my PC specs on a MSI Gaming Pro Carbon x370 Motherboard

Ryzen 1700x

32GB 3200MHz GSkill Tridentz RAM

MSI Gaming X 1080 Ti

2 WD Black 1TB NVMe (one each for Windows 10 and Manjaro Linux)

1 WD Blue 1TB 2.5" SATA SSD (just bought for Big Sur without realizing the GPU bottleneck, cannot return)

2TB Seagate HDD

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I have 2 options now

• Install High Sierra. But then lose on latest updates and XCode. This would be my last resort.
• Add a second GPU (cannot give up 1080ti), which I am fine with. I haven't come across posts which are using dual GPUs in such a fashion. Is it possible at all? Cause I won't be able to return the GPU once I order :D. If any of you can suggest a cheap GPU with decent performance (RX570 or lower if possible) that would be super helpful! Don't want to buy something like 5700XT which might be an overkill. I won't be using it for gaming much.

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For now, I will be installing High Sierra but would want to soon transition into Big Sur once the final version is released. By then I would get a decent idea of what's working and what's not.

Thanks a lot in advance, apologies for the long post!