Do the Mojave or Catalina patchers support AMD PC GPUs or do you need a flashed card for this? In the past, I had used dosdude1's High Sierra patcher to get macOS 10.13 on an older Mac Pro. However, the GPU in this machine is a non-flashed AMD R9 270X, so I couldn't get a boot screen and had to rely on setting the boot drive either before rebooting or setting it from command line.
Recently I tried to see if I could experiment with Mojave and the newer patcher, but I don't seem to get the video card to wake up like it did with the High Sierra patcher. Of course, being a non-flashed card I can't see the boot screen so I can't tell if the USB gets recognized or not, but after letting it sit for several minutes I don't get anything and I wonder if it is going to even work with this graphics card. With the High Sierra patcher, it would eventually come to life so I could install the AMD 5xxx/6xxx patch (though my card is a 7xxx).
Anyone know? I think Mojave or Catalina might be pushing it for the old beast at this point, but any last drops of life I can squeeze out of it before I drop money on an M1 :-)
'older Mac Pro'… specifics would be good.
However, the R9 270X in its HD 7950 guise works fine on a 4,1 with firmware upgrade &amp; a standard 5,1. With an unflashed card you must not use anything which needs the bootscreen - filevault or EFI/firmware lock of any sort.
The smart money was always on keeping the original video card for situations such as these, though neither the GT120 nor the HD5700 can actually run Mojave.
Anecdotally, Mojave is better than High Sierra imho, but personally I wouldn't push any cheesegrater to Catalina.
You'd be wise in any case to very carefully read dosdude's page on Mojave, as it contains a lot of caveats dependent on the precise Mac Pro model.