Max cpu load settings

maxload=45 in asterisk.conf and server with 24 cores and uptime shows cpu load can be 40-50 during the peak hour. However when I use sar to check later on, %user only 6-7% and %system only 13-14%, %idle around 80% on peak hour. Does that mean I can set even higer maxload to like 80 or 100. According to some books, cpu load should not bigger than number of cpu cores, I doubt it. How high cpu load we can go ? thanks.