Hi folks:
Just swapped out my ATI 5870 video card for an nVidia GTX 660ti, going from 1GB to 2GB VRAM, with the hope that I'd be able to take advantage of improved effects performance on MC 8.6.5. Using El Capitan 10.11.6 OSX and MC 8.6.5, it works. The GPU is recognized on launch, and the acceleration is enabled.
The oddity? When I tested the same configuration on MacOS Sierra 10.12.1, the GPU is not enabled. According to the console, it says '2048MB memory required, only 2047MB available'. Ha!
Wonder if this is an easy fix for the next MC point release..? :-)
Best, JIM.