It doesn't mention USB C or Thunderbolt 3 in the XPS 15 9550 guide anywhere so I'm just going to ask it here, is there any possible way to make either of those work with El Capitan?
said guide: http://www.tonymacx86.com/threads/guide-dell-xps-15-9550-skylake-gtx960m-ssd-via-clover-uefi.192598/
said guide: http://www.tonymacx86.com/threads/guide-dell-xps-15-9550-skylake-gtx960m-ssd-via-clover-uefi.192598/