I'm using an AMD Phenom II desktop running Windows 7 that I custom built. I put the system to sleep (not hibernate) then I accidentally shut off the power supply that it was connected to as well, so the system was not being supplied any power. My understanding of sleep is that it needs a little power since it does not save any information to disk. However, when I turned on the system several hours later, it still woke up from sleep and all the windows I had open were restored just as they were before.
How is this possible?!? :O