My desktop PC is running Windows 10 64bit. Instead of shutting it down, I'm putting the machine to sleep. In the past 4 years I've never had any issues with that since the PC is powered from a UPS and PSU is one of the better units (Seasonic X-650).
However, recently I've noticed that the PC sometimes powers down from sleep mode (my estimate would be 1 time out of 10). When turning on, the PC won't start the first time. There's no display output with error code, no beeping signals. The power LED is lit, but nothing happens. Then I have to shut the computer again by holding the power button and start it once more. After that, the PC just starts as it should and runs perfectly.
In the Windows Event Viewer I can see the PC was not shut down properly, but there's no other indication of what might be the issue. In the recent past I changed my graphics card but can't imagine how it could be an issue since the PC is performing perfectly as it should, even under heavy load uninterrupted for many hours.