The Sony XBR43X830C or the Samsung UN40JU6500 for Pc monitor In 1080p And 4K

Im looking at getting this tv the Sony XBR43X830C or the Samsung UN40JU6500 im going to be using it as a Pc monitor and i have a gtx970 to use one of them in 4K mode, how different it will be the 120Hz to the 60Hz when i set the resolution to 4k 60Hz if i run in 4K mode all the time will having the 120Hz not matter, and movie wise in 4K on my pc. i do game, edit videos 4K and 1080P and photos and use my pc a lot, watch movie here and there..