Your question is an oxymoron. If your PC is turned off than no apps can run on the same PC in that state. You need some HW accessing your PC's MOB integrated and battery powered clock to get the system time. This HW should also have a kind of source of power (i.e. a battery), read your clock, compare values and turn on your PC. How about a programmable UPS, or use your sprinkler control unit for manually regulate on/off times in advance, or just set your alarm (clock manual, phone via a program), wake up and use your finger to turn it on. Why even turn your PC completely off? What should the PC do after it is on?

Garavan OPTILUS Inc.