When you enter an average daily load profile, HOMER repeats that profile over and over to create a complete year of data, then it adds some random noise so that every day is unique.  When you import hourly load data, HOMER does not need to synthesize load data so it does not need you to enter the noise values.  We could have made the noise input boxes invisible when you import data, but instead we decided to calculate the noise values from the imported data (which is easy enough) and display them in those input boxes.  HOMER reports those noise values for your edification only.  It does not use them in any way.