Thank you for posting the links. Interesting information. I don't have the mystery wake issue but I took a look at the logs anyway. Since April 14th I have nothing but lines like this…
Apr 21 05:35:12 iMac kernel[0] <Notice>: Wake reason: XHC1
Which Is caused by me pressing a key on my keyboard.
I do remember having an earlier iMac which would wake on its own periodically. I never looked into it but I remember thinking it may be caused by an external HDD I had at the time.
Sometimes issues like these are nearly impossible to track down. I do know things like line noise or temperature can affect almost any digital device. I've had to reboot my DVR on occasion when it failed to behave normally a few times for no reason I can tell other than electrical noise in the AC line.
Short story, I worked at a high end audio company for a number of years. We started selling what was the first all digital receiver. We started getting reports that some of them would turn on by themselves, tune to different channels, adjust volume on their own etc. We thought something was wrong with our customers. However, I brought one home to evaluate and one day, my g/f left the house to go shopping and when she returned the stereo was playing away, she was sure she had turned it off before she left so was afraid to go inside thinking someone had broken in. The manufacturer eventually found out they had a bad batch of chips that would misbehave in a certain temperature range.
Sometimes stuff happens.
