This doesn't look like a gaming machine to me at all. A gamer would want to replace those soldered-in Fire Pros and get a new GPU every year or so. Fire Pros themselves are way overpriced to only be used for gaming. Also, the state of Thunderbolt GPUs is pretty bad right now.
I agree it's not a gaming machine at all - the choice of fire pro's tells you it's a workstation.
But don't look soldered in to me - looks like the boards drop in vertically.
It's not PCIe - so you'll have to go to apple for a new card or two - but it's not on board either.