Can't figure out what's waking my homebuilt Z170-Deluxe desktop machine right away.
I've tried going into sleep state from both Win7 and Win10 (dual-boot system), and the exact same symptom occurs regardless. The machine does go into sleep state, and the power light on the case starts to blink. And then within just a few seconds something wakes it back up and the machine starts up again, coming right back to whichever Windows OS I was last in.
Obviously there is something in the hardware itself (either on the motherboard or in some internal/external device) which is waking it up. But I cannot determine which one.
I've looked at POWERCFG /LASTWAKE but it shows "PCI-to-PCI bridge", which is meaningless to me. Device Manager shows about 7 of these devices, with nothing specific about any one of them.
Is there some other way I can diagnose this? I really would like to put this machine to sleep, if only I could overcome its "instant re-awakening".