[EDIT]hmmm.....whats going on at AMD? (and history of 3Dfx Rampage)

[SteelCrysis]

http://www.tomshardware.com/news/apple-v...34667.html

Vega's inclusion is the most surprising aspect of the iMac Pro. Apple previously restricted most of its iMacs to integrated graphics. This made them ill-suited for gaming--concerns about many games not supporting macOS aside--simply because the devices weren't powerful enough. We don't know what kind of performance Vega will offer at 5K resolutions, but it's bound to be better than whatever Intel's integrated graphics could provide. (To be clear: We assume Apple would've picked a processor with onboard graphics if it weren't going the Vega route.)

But we suspect Apple's sudden fondness for dedicated graphics results from its push to join the VR revolution. You're not going to get a worthwhile VR experience on the graphics found in the current iMac, Mac Mini, or even Mac Pro. Combine the graphical horsepower required to power VR with the need to push a bunch of pixels to a 5K display, and you have a pretty good reason to use modern graphics. Given its existing relationship with AMD, then, it's not surprising that Apple picked the soon-to-debut Vega GPU.

The iMac Pro is set to launch in December with a starting price of $4,999.