So I've inherited (so to speak) a MBPr early 2015 i7, 16GB ram, 512GB Hdd. I know the newer USB-C/TB3/Dongle books support external GPUs. Is it possible on this model with TB2? I'm assuming bandwidth of TB2 might limit or steer me in the direction of certain cards as well. Anyone gone down the eGPU path on a macbook?