There are? That will work with High Sierra when it is released? I watched a youtube video and they said it is possible to currently use an external card with Bootcamp but it only works with 2 computers, is hellishly expensive and is fiddly to set up (no good for me as a computer novice).
If these things will work with bootcamp in the future with a tricked out late 2013 iMac I am all over it
I currently run an external GTX 1060 on my 2013 mbp and it's amazing in windows. Doesn't need a secondary computer, just the card and the box. My particular machine is known to be troublesome with egpu's though, sometimes I run into issues when starting up from off (all the way off). When that happens I boot without the egpu, run a script, the reboot with it connected.
Works very good in Mac, works amazing in windows. I suspect most of the disparity between the two os's is the driver quality (beta on Mac) but either way it's mind numbingly powerful in windows, no issues, and no secondary computer required, just that script when starting up from cold every now and again.
Edit: I run sierra, the 1060 worked even better in windows when I had El Capitan (no need for the script) but didn't work at all on the Mac side, in hindsight I could have gotten a 780ti for the same price with the sameish performance and it would have worked on both without the clunky beta drivers.