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.

  • As you describe it, one hardware piece (probably the graphic card) is not allowing your PC to wake up. It doesn't shut down, it just can't wake up. Does it have the more up-to-date drivers? – fernando.reyes Feb 28 '17 at 14:09
  • I'm pretty sure the issue is not that the PC cannot wake up but that it shuts down. The power button is blinking in sleep mode. When this issue occurs, it does not blink at all. – Duken.Jr Feb 28 '17 at 14:12
  • Your computer is definitely ON and not showing an image on the screen, it's a graphic card problem. – fernando.reyes Feb 28 '17 at 15:49
  • Not so sure, if BIOS failes to initialize a component (CPU/RAM) it let's you know there's a problem by beeping. In my case, no such thing happens. Also, how could the GPU fail to initialize once and then few seconds later work perfectly and continue to do so without any hiccup for days/weeks before the issue occurs again? – Duken.Jr Feb 28 '17 at 16:06

If the power button is blinking and the screen is black, it is sleeping. Press it once to wake it up. If the light on the button is off completely, the computer is shut off. Again, you press the button and it will wake up, but it'll take longer.

SO, if the light on the button is ON and NOT BLINKING, then don't touch the button. Press a key or slide your finger on the track pad to wake it up. If you press the button when the light is on, it will shut the computer off. Sometimes I mistakenly think that the computer is off without looking at the light (which is on) and when i press the button it will shut the computer down.

Hope this helps!

  • 1
    Frankly, from this answer I get the idea you think I've never seen a PC before in my life. I've been working as a software developer for over 15 years and wouldn't ask simple questions the answer could be googled to in less than 5 minutes. NOT HELPFULL at all. – Duken.Jr Feb 28 '17 at 15:21
  • Not trying to sound like that at all. Just trying to share my two cents. No hard feelings, and hope it all works out. – Calpals Feb 28 '17 at 15:29
  • No hard feelings whatsoever. But you are answering a completely different question "How can I tell if my PC is powered on, powered off or sleeping", not the original question "What is the reason for my PC unexpectedly turning off while in sleep mode". – Duken.Jr Feb 28 '17 at 15:30

I used to do a lot of work on peoples' home desktop computers and discovered that there is one achilles heel that is common to everyone. Especially cat owners. And especially when they get to about the age of yours.

If your power supply overheats it will be the first thing to fail.

Most often it is because of an accumulation of dust (or cat hair) on the P/S fan.

So I recommend you check that out and see if perhaps a long blast of canned air would help clean things out so it can run at full speed without airflow impediments. Use the canned Freon to make that fan spin fast, then make sure all your vents are as clean as possible.

Good luck!

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