When I put the system in sleep mode, it keeps making a sound (maybe the drive?) every few minutes although nothing shows on the screen. what could be causing this? Thanks.

Another source of the problem: System Preference > Energy Saver: disable "Enable Power Nap," which otherwise allows your Mac to back up using Time Machine and periodically checks for new email, calendar, and other iCloud updates. Was driving me crazy!

Do you have an external drive, mine makes a noise sometimes when closing down

It sounds to me like only the Display is sleeping and the Computer is not going into full sleep mode.

Please visit > Mac OS X: Why your Mac might not sleep or stay in sleep mode

In Computer sleep nothing is running and it should be quite.

In Display sleep the Hard Drive, cooling fans and background processes run.

I have the same problem with my new iMac (mid 2011). When I click Go to sleep mode, the display sleep down but I can hear fans and hard disk drive every minutes. So the Mac isn't really sleeping and is consuming electricity...

I tried :

- disable file sharing

- disable bluetooth activation

- disable wake on lan

- 'turn off hard disk as soon as possible' checkbox is checked

- no external drives, no USB devices

- no Ethernet cable, Wifi disabled

- no external display connected

- disable "Locate my Mac" from iCloud settings

- tried the Mac OS Safe mode, nothing better

And when I want to wake up the Mac, I press a key on the keyboard, the screen login appears immediately. So it doesn't go in the sleep mode...

I don't know what's more I can do...

Thanks in advance.

Excuse me for my bad English !

Found the solution here : https://discussions.apple.com/thread/3388262?answerId=16376294022#16376294022

There were two documents in the print's job list. I removed them and my Mac can now sleep 🙂

I hope this will help you.