My fan doesn't turn off when my 360's in ...

I thought the Spring Update%26#39;s StandBy mode (also known as ''Low Power mode'') was supposed to turn off the 360%26#39;s fan when it%26#39;s downloading stuff. I mean, I%26#39;m not complaining that much as it%26#39;s really quiet, but it%26#39;s still on, Anybody else have this problem?