Irony here: my RX550 OOB works flawlessly running Win10 64bit in 10-bit 4K at 60fps on my ancient, unmodded, 10 year old MacPro 1,1 with a pair of 5160's @ 3GHz and 6 Gigs of RAM on a Bootcamp partition. No other video card is in the 1,1. Cold boot is handed off directly to the RX550 that shows a few seconds of black screen and blocking artifacts with no Apple logo. Boot continues directly to Win10 in 4K. The RX550 is so power efficient, its fan often doesn't turn at all unless e.g. its using video benchmarking software or running full-screen 4K YouTube video which it does without a bump. In fact the 1,1 that I'd come to know over the years as an NTSC-rendering noisy space heater just a breath away from being tossed into a recycling bin, now runs cool and whisper quiet like a totally new machine. It can even run the Windows demo version of DaVinci Resolve in 4K!
All Win10 features work and all AMD updates for the RX550 are stable. The old beast runs just like a new Win10 native rig and accepts any old PCIe card or USB dongle I try, including devices for which there has only ever been dicey or rudely canceled support under a major upgrade version of OSX e.g. my expensive CalDigit USB3.0 and eSATA PCIe cards that now work again. Wonderful, if running Win10 on a 1,1 is the goal! I installed Win10 to see whether the RX550 could even work on a 1,1 just to prove a point and learned much more than I expected.
Ubuntu Installer recognizes and can use the RX550 but won't install itself on the 1,1 because a message comes up saying the 1,1 is "too old" with no further explanation.
The 1,1 was no longer officially Apple supported by 2010 which left the rather limited OSX 10.7.5 as its final supported OS. As I've proven that an RX550 will run perfectly in 4K on the oldest macpro tower made under Win10 and Ubuntu Installer, I'm hoping Clover or Multibeast etc developers can find settings to get the RX550 to work (hopefully in 4K) in older and newer versions of OSX on all classic MacPro tower platforms. AMD refuses to supply MacOS drivers for the RX550, instead referring users to Apple. As a non-programmer, I'm wondering how much of the work done by the RX550 (not to mention other cards in the Polaris 12 family) is from the firmware on the card itself vs. a driver that is loaded into the computer? Could utilizing an RX550 in an older macpro tower be as easy as playing around with Clover, Multibeast etc. long enough until the correct settings are found?
