Computer turns on/off every 5 seconds

January 28, 2012 11:43:29 PM

Hi. Im fairly new to working with computers, so please bear with me. About 2 weeks ago the monitor for my desktop computer refused to wake up from sleep mode. To try and remedy this problem, I hard-powered down and tried to reboot it. Instead, the computer booted up for 5 seconds then shut down. 5 seconds later, the system tried to power up again but still only stayed on for 5 seconds, and the only way to stop this was to turn off the power or unplug the PSU from the back. About two months ago I bought a new graphics card and PSU, an ATI Radeon 5770 and a Cooler Master eXtreme Power 500w PS. After researching a bit, it seems that the PSU is at fault. I have read that the fault lays in insufficient power making it to the mobo, but as it worked fine before, i dont think its any loose wiring somewhere.

Note: I tried re-seating the RAM as a possible solution to the monitor not waking up, however this was after the computer stopped working.

Any help would be greatly appreciated. Thanks!

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house70

January 29, 2012 12:06:28 AM

First things first. Make sure the power or reset buttons on the front panel are working properly, are not shorted out etc (that goes for their respective connectors on the mobo, as well.). Inspect the capacitors on the mobo to look for bulging. If all this is well, try borrowing a PSU and temporarily replacing it.

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NoodleSoup17

January 29, 2012 12:30:15 AM

house70 said:

First things first. Make sure the power or reset buttons on the front panel are working properly, are not shorted out etc (that goes for their respective connectors on the mobo, as well.). Inspect the capacitors on the mobo to look for bulging. If all this is well, try borrowing a PSU and temporarily replacing it.

How should I test these? Also, I'm not sure what the capacitors would look like even if they hadn't bulged. Specification please?

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house70

January 29, 2012 12:39:10 AM

You can test the power and reset switches by disconnecting the wiring that goes to the mobo (from the power and reset buttons) and using a small flat screwdriver to temporarily short the power pins. The system should start up and, because possibly faulty wiring is not connected to the pins anymore, it should stay on. While at it, make sure there are no impurities on the opposite side of these pins (where the soldering is), something that can harbor a small bug or a hairball or something that could cause a short. Remotely possible, but not impossible.
Capacitors: they're little cylindrical components, most of them close to the CPU socket on the mobo. Can't miss them. The lateral cylinder wall is usually blue or black, while the top is shiny.

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