Chosen Solution
Technically Apple does not support Catania on these older systems. While there are tools to allow it, it really doesn’t make sense if you only have 8GB of RAM on the system and have a HDD as your primary drive. Changing out the GPU board to one that can support Metal is not trivial! Apple uses a custom version of board which has its own firmware. So you will need to reprogram the boards firmware to allow a non-Apple GPU board to work and depending on which on you may loose functionality like brightness adjustment or Startup Manager or other startup commands. While a fun project in the long haul its not worth it.
