The only point in having an FPS above the monitors rating is to increase the FPS at graphically intensive moments in games. For example, if I average 80 FPS, that could mean I am getting 140 in some parts and 20 in others. If I can increase it to, say, 120 average, I could then het 150 and 90. While the high number went up, what is really important is that the low number is now higher than the maximum that the monitor can display.
Now, these umbers are an example only, but most people who strive for FPS never take these things into account. that is one of the reason I think ATI doesn't get enough credit. Everything is always done as an average and the never account for the highs and lows. If a card averages less, but the low id never lower than can be percieved, it will appear to be a lesse card while actually giving better performance.