I posted something a little while back about my troubles with getting Vista to stop waking up randomly in the middle of the night.
Enough was enough, so I decided to go for a clean install to see if that fixed it and a number of other problems I had. And what do you know, it STILL woke up randomly, and the wake cause was still “unknown”. Extremely frustrating considering it was a completely new installation.
I dug around a little more and in the end had to settle for this handy tip: If your computer keeps waking up (and it might be my motherboard/OS combination it appears, it looks like an Asus thing…) run these commands and it will completely disable ACPI wakeup:
1. powercfg -setacvalueindex scheme_current sub_sleep bd3b718a-0680-4d9d-8ab2-e1d2b4ac806d 0
2. powercfg -setdcvalueindex scheme_current sub_sleep bd3b718a-0680-4d9d-8ab2-e1d2b4ac806d 0
3. powercfg -setactive scheme_current
This way, whether on AC or on DC, the Vista will refuse to wake up if the motherboard sends a call asking for it. This is good if you get random wakeups, but it does of course mean that if there is a legimate reason that your computer should wake itself (e.g., Windows Media Center waking to record a program) it will no longer do it. However, you can re-enable it if you need this functionality for, say, a day or two, by simply swapping the 0’s for 1’s in the above commands. For me, it’s far more attractive to have a sound night sleep without your machine coming out of sleep for no reason!