My PC restarts without any notice?

Mine restarts because at a certain time it is to do its updating. i don't think this has anything to do with your computer but just to let you know.

first u should see the inner cpu fan and smps fan, if both r rotating well then u just change the power supply unit of u r cpu it may resolve ur prob

Are you fan rotates? Whether your hardware is connected with tight? Your files not corrupted? If your fan not rotates and your hardware isn't connected with tight also this can cause restarting if your files is corrupted and CPU getting hot.

I faced the same problem many weeks ago. While working, the PC would automatically restart. The main cause is electricity. It could be because the electric supply goes off and comes back again within a second. It hard to detect because it happens very fast. Other reason is low votage. Switch off any other appliance which uses too much power ex: Iron box. Another reason is improper wiring. Make sure the plugs are properly fitted in the socket. Also try opening socket box to check if the wires are properly fitted and the screws are tight. My problem got solved after I fixed above. Another less likely reason could be that the RAM is loose on the motherboard. I hope this will help you.

Try to remove the cover of your main box...then start your system, if it restarts again, check the cpu fan, is it rotating? if not check the power supply for the fun of course do this by shutting down first your PC. Check all connections inside your PC.. Remove them put them back again...If symptoms persist you may have a busted power supply try to replace them..or try to reinstall your OS this will remove all virus, worm etc in your system...Hope this helps....

Its possible your pc is getting overheated. If your CPU get to hot it just shuts down, without a warning or so. Check if your CPU cooler isn't full of dust. If so try to clean it out. If your do not want to open your pc for nothing try monitoring first. This is a good tool for it. http://www.almico.com/speedfan.php If your CPU gets near 90° its getting overheated. I know my CPU went till 110° before shutting down. Overheating isn't that big of a problem. Cause CPU's are secure to it. They'll shut down before burning up. Ofcours if you keep overheating it lets say couple of months, this security will brake. I hope I could help you

There're many reasons for a restart. Check the following possibilities -It's dued to an automatical update: verify your programs and modify parameters if necessary. -The ventilator in the CPU box can't push out all the heat trough it runs its best, and so the current will be cut off to protect devices from melting down. It seems your case. -.... still more reasons, but I don't know.

I doubt whether your computer has been infected by the computer virus. I love China

I think there might be certain serious prob with your computer you may need it to send to the seller of it for a check..

I think, as said before, heating issue. Most computers got some kind of system so it just shuts down, so it doesn't start to melt or burn.

i think that your computer has a big problem. i think that you better it fixed on repair center. cause it is hard to repair or find the problem by your self. there can be many possible problem for that. for me i think that it can be the power supply itself. or it can be loose cord or something. i have experienced that problems before too. but i could not figure it out what was really wrong. anyways, i have thrown the old one and just got a new cpu instead.

same with me, right now, my computer have problem like yours, even i reinstaling my Windows, it still restarting periodically. But i think, it not really bugging me.

Your computer might be infected with a virus or any other malware. Clean your PC or just format your hard drive and have a clean install of whatever operating system you are using. Try scanning and cleaning it using tools like Norton Antivirus, Malwarebytes' Antimalware, Bitdefender, AVG and Kaspersky. Good Luck!

If the computer has no power, when you turn it on, then it's most likely the power supply, or the cables from the power supply to the motherboard may be loose, or not securely in place. The problem could also be that the hard drive is about to fail. I would recommend that someone do a visual inspection of the system board and check the power supply wires first. Secondly, I would also do a scandisk on the hard drive check for bad sectors.