Mac Hibernate Sleep Mode, quiet and no hard drive sounds
I'm assuming your mac is connected to the power cord, if so, you should check the power adapter section:
- uncheck wake for network access
- uncheck power nap
I had the exact same problem, it would be constantly starting and stopping (in my case, it was the fans), until one day I accidentally knocked the power cord and it fully stopped. Then I got curious and found the settings.