You are fairly limited in options for getting thunderbolt on PC, but fortunately, its actually the best option at the moment. That's an X99 motherboard with the optional thunderbolt card(not every X99 board has the option so shop with that in mind). I believe all the X99 mobo's are socket 2011-3, so look for the same in a cpu(i7 6800K is what I just moved to). I would call 700 watts the bottom choice for PSU. Add 32GB of RAM and a Samsung SSD and recycle your recording/samples drives and that should come in right around your budget
