Right so I'm up early because every time I shutdown my PC there's a 50% chance of it coming on 20 seconds later . I'd already done the usual stuff, update BIOS, alter UEFI settings, disable wake permissions from various items in Device Manager, etc. Here's a way I've stumbled across on how to do it (presumably) for Windows 10. Do this right after the PC turns itself on: Open CMD Type powercfg /lastwake As you can see the culprit is listed as the network adapter. I'm sure I had already disabled that via Device Manager but let's continue... Now if you want, compare the list of devices that can wake your PC Type powercfg /devicequery wake_armed Now to disable it, type powercfg /devicedisablewake "your device here" Give that a go. If problems persist then repeat this and see if another device needs disabling. If you want to see what else you can do with this tool then just type /? after any command, i.e. powercfg /? or powercfg /devicequery /?