Different Peak values for different Time Range in the period of time

Hello

We are monitoring some interfaces from our Netgear Switch, but if we evaluate the bandwidth in that last 3 hours the maximum value is around 30MB/s but if I choose the Last 5 Minutes I got peaks about 45MB/s and even found values over 100MB/s. If I increase my time range the Y-axis is different if I choose less time.