85Hz doesn't exactly mean 85fps
You see, 85 fps is displaying 85 constant images within a second. An 85Hz refresh rate means that your monitor blasts your screen with electrons 85 times a second. What this means to you is that since your monitor is NOT on all the time (neither is a light bulb, btw--works on the same principle) and only fires 85 times a second at 85Hz (think of it like an AC waveform) that only 85 changes can occur on a pixel in a second. Thus, you're limited to 85fps because going above would just get discarded. However, even a single frame is being refreshed at 85Hz. For example, playing a 30fps video on a monitor running a 60Hz refresh will actually fire the electron guns with the same frame twice before it changes. Your monitor is flickering. A projector displays an image continuously--unlike your monitor.
I dont think I made it very clearly, but what I said is factual.