MP 1,1-5,1 What is the highest flashable Radeon video card to have boot screen for MacPro5,1 & MacPro4,1?

[timidhermit]

Despite having read the FAQ here and elsewhere and watching numerous YouTube on this topic, I am totally confused on what video cards are supported beyond the ATI Radeon 7950 for Mac for my MacPro4,1 and MacPro5,1. Here are my requirements:

1. The video card needs to be flashable so that it will support the stock Apple EFI boot screen (not a third-party boot screen). This is because I need the ability to choose to boot to macOS installed on an external drive and Windows installed on an internal system drive (note that Windows was not installed using Boot Camp but a direct GPT/MBR traditional install).
2. The card must be installable in my MacPro without using power hack (I don't want to do the Pixlas mod).
3. Either Apple stock video driver for Windows 10 and 11 (and macOS) or an "official" video driver from AMD is available. In other word, I want to avoid using OpenCore if possible (I am aware that this will prevent me from installing current macOS versions).

With the above requirement, what is the highest / latest Radeon-based card I can get for my MacPro5,1 and MacPro4,1?

 

[tsialex]

Despite having read the FAQ here and elsewhere and watching numerous YouTube on this topic, I am totally confused on what video cards are supported beyond the ATI Radeon 7950 for Mac for my MacPro4,1 and MacPro5,1. Here are my requirements:

1. The video card needs to be flashable so that it will support the stock Apple EFI boot screen (not a third-party boot screen). This is because I need the ability to choose to boot to macOS installed on an external drive and Windows installed on an internal system drive (note that Windows was not installed using Boot Camp but a direct GPT/MBR traditional install).
2. The card must be installable in my MacPro without using power hack (I don't want to do the Pixlas mod).
3. Either Apple stock video driver for Windows 10 and 11 (and macOS) or an "official" video driver from AMD is available. In other word, I want to avoid using OpenCore if possible (I am aware that this will prevent me from installing current macOS versions).

With the above requirement, what is the highest / latest Radeon-based card I can get for my MacPro5,1 and MacPro4,1?

Almost any modern AMD PC GPU can be make to work with native pre-boot configuration today, so, this is not a problem. Power envelope restricts your choices to some GPUs. For everything that you listed, a reference model Radeon VEGA 56 with the firmware switch set to lower setting connected to an eVGA PowerLink is the most powerful and "newer" GPU that fits all three requirements.

Newer cards that fit the power requirements, like Radeon RX 5700 or RX 6600/6600XT, will require unsupported macOS releases/OpenCore. RX 5700 require Catalina, while RX 6600/6600XT require Monterey

You will need to add EnableGop EFI module to the Mac Pro firmware or to the GPU firmware, easier with a BootROM reconstruction.

 

[h9826790]

Some additional points on top of Tsialex's reply.

because I need the ability to choose to boot to macOS installed on an external drive and Windows installed on an internal system drive (note that Windows was not installed using Boot Camp but a direct GPT/MBR traditional install).

Despite almost all modern AMD GPU with factory firmware (non flashed) can show native boot screen on cMP with EnableGOP. What's the problem of using 3rd party boot screen? e.g. RefindPlus can do exactly what you want.

...video cards are supported beyond the ATI Radeon 7950...

...boot to macOS...

...what is the highest / latest Radeon-based card...

You have to tell us which macOS you are actually talking about. Otherwise can't give you accurate answer.

Either Apple stock video driver for Windows 10 and 11 (and macOS) or an "official" video driver from AMD is available. In other word, I want to avoid using OpenCore if possible (I am aware that this will prevent me from installing current macOS versions).

Sorry, I can't see the relationship between "avoid using OpenCore" and "having official GPU driver avail". Can you explain a bit more?

I totally respect your own choice if you want to avoid OpenCore. However, since you said "In other word", which means somehow you believe OpenCore is related to that official GPU driver availability.

Anyway, despite Apple never support cMP to run Windows 10 / 11 (which means, no Apple driver avail). When you are talking about "flashable" card, you are talking about "non Apple" card already (which also means, no Apple driver avail). Therefore, no matter which card you choose, they all have Windows driver from AMD by default.

I am totally confused

From your questions, I believe you are really confused. I think we better clear your confusion then move forward. Otherwise, you may base on some wrong assumption to make the wrong move.

 

[avro707]

Despite having read the FAQ here and elsewhere and watching numerous YouTube on this topic, I am totally confused on what video cards are supported beyond the ATI Radeon 7950 for Mac for my MacPro4,1 and MacPro5,1. Here are my requirements:

1. The video card needs to be flashable so that it will support the stock Apple EFI boot screen (not a third-party boot screen). This is because I need the ability to choose to boot to macOS installed on an external drive and Windows installed on an internal system drive (note that Windows was not installed using Boot Camp but a direct GPT/MBR traditional install).
2. The card must be installable in my MacPro without using power hack (I don't want to do the Pixlas mod).
3. Either Apple stock video driver for Windows 10 and 11 (and macOS) or an "official" video driver from AMD is available. In other word, I want to avoid using OpenCore if possible (I am aware that this will prevent me from installing current macOS versions).

With the above requirement, what is the highest / latest Radeon-based card I can get for my MacPro5,1 and MacPro4,1?

Official drivers are available for RX6600XT, but only in Monterey - and you'll need Opencore to make that work.

We really need to know what MacOS you have. My guess is you might need to flash an RX580, if you can find one new, otherwise you might be buying second hand cards, good luck.

For my needs, OpenCore (Martin Lo's package), current Monterey and the RX6600XT flashed (using my 7,1 for that) is the solution. I use that every day.