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Mike Richardson

macrumors regular
Original poster
I am getting an error that says "This version of Mac OS X is not supported on this platform! Reason:Mac-27AD2F918AE68F61".

I have an NVMe drive that is partitioned with both Monterey and Mojave. It used to boot Mojave fine a long time ago, when I first installed OC?

If I google "27AD2F918AE68F61" it seems to be the identifier having to do with a MacPro7,1 and this is what I see in my EFI/OC/config.plist file.

I'm not sure why this identifier is being used (I seem to recall a guide online that recommended pretending to m. I think I was trying to get accelerated video to work with my RX580 (which it does right now).

I don't want to try another identifier in fear of bricking the boot unless someone else can report that such identifier works for them.

I also don't want to break acceleration in Monterey.
 

h9826790

macrumors P6
Apr 3, 2014
16,620
8,554
Hong Kong
Change the board ID to Mac-7BA5B2D9E42DDD94.

Both Mac-7BA5B2D9E42DDD94 and Mac-27AD2F918AE68F61 can be used to fully activate HWAccel for your RX580.

But Mac-27AD2F918AE68F61 doesn't support Mojave.

The downside to use Mac-7BA5B2D9E42DDD94 is that iMac Pro only has one build in monitor. Your graphic card's framebuffer may be affected. Therefore, you should also add agdpmod=pikera into the boot argument to alleviate this issue.

But if your monitor stay black after switch to Mac-7BA5B2D9E42DDD94, try other ports first. Some of the ports usually still working.

This is an example of how to change from Mac-7BA5B2D9E42DDD94 to Mac-27AD2F918AE68F61. What you need to do is the other way around (and add agdpmod=pikera into the boot argument).
 

Mike Richardson

macrumors regular
Original poster
Looks like I am using Open Core Legacy Patcher (it was also out of date so I went ahead and updated it).

Selected iMacPro1,1 to spoof as and rebooting to Mojave now.

Edit: Now in Mojave. The other day I just wanted to play a game, this time I needed to format a spinning drive with HFS Extended Encrypted and they took all those options away, even though it mounts just fine.

Thanks for the info about the dual displays also. I'm only using 1 right now but I have had a dual setup before.
 
Last edited:

h9826790

macrumors P6
Apr 3, 2014
16,620
8,554
Hong Kong
Edit: Now in Mojave. The other day I just wanted to play a game, this time I needed to format a spinning drive with HFS Extended Encrypted and they took all those options away, even though it mounts just fine.
Format the drive, not the partition / container.

You cannot format a partition inside an APFS container to HFS+.
Screenshot 2023-08-28 at 0.35.30.png


But you can format the drive itself to HFS+.
Screenshot 2023-08-28 at 0.35.48.png
 
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