Computer turns off by itself suddenly

By dr_nishis ·
Our desktop keeps shutting down. Let me describe the problem in detail:

1. One day, the computer suddenly shut off when we were working on it- (no warning, not a proper shut down, it just went off- like a light bulb switches off J )

2. We turned it back on and it turned back on normally. Then when it went to the login screen, and we logged in it turned off immediately like before

3. When we turned it back on again, it shut down when it reached the login screen (before we could type the password)

4. It never stays on long enough to do anything like run an anti-virus program etc

5. We then tried to start it in safe mode but it still turned off so we could not do anything on safe mode either.

6. We tried disconnecting the monitor but it still stayed on for some time and turned off.

7. We tried disconnecting the keyboard, mouse etc. But again no difference. Still turns off every time in the first ten to fifteen mins, sometimes even in 2 mins.

8. Yesterday, our friend changed the power supply and put in a spare one (not new one) and it seemed to work fine. But when we got home we kept the comp on for 25 mins and it shut down again. We turned it on but again after 20-25 mins it turned off.

So this is the story. Any idea what it could be?

Other details: The PC is a Dell Insipron (2350) around 5-6 years old, runs Windows XP, antivirus- we use Rising Antivirus.

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Reseat the CPU

by Jacky Howe In reply to Computer turns off by its ...

Power Supply
A common problem is the System mysteriously shutting down, especially when playing games. This is often caused by the Power Supply being Overloaded, these safety measures ensure that it automatically shuts-down.
Over-voltage Protection
Short-circuit Protection
No-load Operation
Over-current Protection
Over-temperature Protection (Optional) Not all PSU's support this feature

If you are experiencing these problems you can test your PSU using the instructions below or purchase a more adequate Power Supply. Do a Google for Antec brand PSU's as they are by far the best quality.

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Central Processing Unit
Faulty Fans, Dust and Grime build up on the Heatsink restricting air flow. Remove the Power cable from the rear of the System and disconnect the Video cable. I would give the inside of the case a blowout with compressed air. When blowing air through the fans make sure that you physically stop them from spinning, as they may generate power and damage something. Use an Anti-Static Wrist Strap to ground yourself or by placing the back of your hand on the Power Supply Unit and not moving your feet. This will prevent electrostatic charge from building up and by not taking this precaution it is possible that you could inadvertantly cause damage to the PC from an electrostatic discharge.

Then remove the Heatsink, giving it a thorough clean and reseat the CPU applying new CPU grease. If the Fans spin freely when you give them a spin they are probably OK. If there is resistance replace them.

Clean the golden edge of each memory stick with a soft rubber/eraser, remembering not to touch the golden edge of the memory stick. Check with one stick at a time, remembering to disconnect the power from the PC.

Also check the Capacitors around the CPU for swelling or bulging.

As the capacitor ages, its capacitance decreases while its equivalent series resistance (ESR) increases. When this happens, the capacitors no longer adequately serve their purpose of filtering the direct current voltages on the motherboard, and system instability results. Some common symptoms are:

* Not turning on all the time; having to hit reset or try turning the computer on again
* Instabilities (hangs, BSODs, kernel panics, etc.), especially when symptoms get progressively more frequent over time
* Vcore or other system voltages fluctuating or going out of range, possibly with an increase in CPU temperature as the core voltage rises
* Memory errors, especially ones that get more frequent with time
* Spontaneous reboots
* In case of onboard video cards, unstable image in some video modes
* Failing to complete the POST, or rebooting before it is completed
* Never starting the POST; fans spin but the system appears dead

Remove the Power cord from the PSU to discharge the Capacitors in the Power Supply. Then press the Power button for 10 seconds to discharge the Capacitors on the Motherboard.

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Probably a PSU or Capacitor issue

by Deadly Ernest In reply to Computer turns off by its ...

If you can, try another power supply of a higher power rating, most systems usually come with the minimum PSU to run the system as is and adding extras means you need a bigger psu. Often it'll work for a while and then fail.

If a bigger PSU doesn't work (try borrowing one as it's cheaper) then it's likely a stuffed capacitor. Unless you're very good at identifying stuffed capacitors and replacing them with a soldering iron, you're better getting a new motherboard.

Third likely culprit is a faulty CPU so try a similar CPU from another system and see if that changes it.

A left field cause may be a faulty setting in the software sending the system into hibernation - I've seen this type of issue with the software sending a system into hibernation and the hardware is older and not really able to hibernate and reawaken properly, so the hibernation signal becomes an immediate power off signal as it isn't a normal shut down signal. But this is rare now days.

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This sounds like a Heat Issue

by OH Smeg Moderator In reply to Computer turns off by its ...

Where the CPU is reaching a set temp and shutting down.

Start off by opening the BIOS and checking the Temp that the M'Board is set to to throttle back after the set Temp is reached and change this to at least 75 Degrees Celsius.

If this is set to that temp then you need to look at the M'Board for any leaking/bludging capacitors and repair as possible. This generally involves replacing the M'Board.


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