Well.. at least to support ye-olde 3.3 fully! (3.3 is basically like DX11.. the latest is something like 4.2..) - supposedly it runs 3.2 but I'm not convinced.. I can see the logic of avoiding 4.x as it's too new and a mess...

Which basically means that the only thing buying a higher end graphic GPU in an apple is that it goes faster by clock speed and number of pipelines.. nothing about using the (now standard) features available - a PC and linux have more advanced graphics sub-systems!

I'm having to use OpenCL to render 3D volume visualisations rather than OpenGL!

Oh.. yes.. it is astronomy related ;)