My late 2012 mac mini connected to a 4K monitor. I can option to lower the resolution by choosing scale, did it to get 1080p so that I get 60hz but unfortunately I still get the only two options that I get when I am at 4K resolution. 29 and 30 hz. I know the monitor can do 60hz, I have connected another computer (custom made pc) and I get 60hz through DP just fine. I have the Mac connected through DP too. Am I doing something wrong?