Bought my first mac a 2013 13'' air i5/256gb on Monday and whilst I've been getting to grips with OS X I've noticed the mac making a strange whining noise. Particularly evident when I shutdown the mac and another time I noticed when I was installing office 2011. It's almost a cross between a transistor whine or a quiet hard drive seeking sound. Also when I resume from standby I hear a short clicky whine almost like a hard drive click. At first I thought it was the fan but I'm not sure and seeing as there's no other moving parts I'm not sure what it could be ? Or is this normal behaviour?