Windows 7: Computer suddenly turning off while running.

My PC acting weird for last two days. While using it is suddenly turning off. Its not shutting down but just powering off. Sometime it automatically restarts otherwise it just stays off.
If it stays off I cannot start from CPU. I have to turn off UPS then turn it back on before the power button in CPU works.

I had some monitoring utility installed (Nvidia system monitor and Core temp) and both show the CPU, Graphics card and MB temp are in range of 40-60 when this happens.

This happened to me once when I was viewing videos full screen. Other when I was browsing ( I was using Mozilla and with lot of addons, sometimes it consumes a lot of memory and processor.)



I also checked the CPU fans and case fans and they are working.

Sounds like a failing UPS. Try disconnecting the PC from the UPS and plug it straight into a wall outlet or a simple power strip and verify if the same symptoms still occur.

UPS is going fine. Its a UPS from Wipro and it has some post when we startup and its not giving any warning.

Looks like my SMPS busted. I had an old low power SMPS. Just tried it and its working.

Thank you for letting us know what the issue turned out to be, and congradulations on figuring it out yourself. If you ever need help with naything else, we are always here.

You may also mark this thread solved if you are ready to do so.

This is solved. Before going something in detail.

Since SPMS has warranty seal, I never opened and cleaned the dust from it. What happened was due to dust, spindle of the smps got stuck. So the fan stopped and the smps got heated up, burning some components. Instead of burning, some parts came loose because the solder in them melted. . When I opened it up (after it blew away) I couldn't turn the fan blades with my fingers.

I got the fan working by opening it up and putting some oil in it. But if anyone have any idea on cleaning SPMS fans without breaking seal, please share.

Only thing I know to do is use a can of compressed air to blow dust out of the unit. You need to so regularly to make sure the same situation does not occur.