Today my computer is always showing a black screen on booting and no signal on monitor, but the monitor is working.

The BIOS message on boot isn't showing up. I thought the problem was my graphics card but it wasn't. I tested by removing the graphics card and tried it with the onboard graphics (VGA, DVI & HDMI). Pulled out the CMOS battery for 10 minutes. I also removed the RAM. Tried every module in every slot alone etc.

CPU, graphics card and tower fan are running. The HDD seems to work because of spin up sound.


My computer was turned off for about 30 minutes and now when I boot, everything is working like normal.

What was the the problem?

My Hardware:

  • AMD Phenom II X4 945
  • 4x 4GB Kingston KVR1333D3N9K2/8G
  • Samsung 320GB HDD

I hope you can give me some tips about the possible source of the failure.

  • once its done booting, does the OS display? if so, if you hit Tab while the black screen is showing, does anything appear? – Frank Thomas Apr 9 '13 at 18:08
  • It doesn't boot normaly. BIOS is NOT showing up. But look what happened, added it to my question. – Mark Hähnel Apr 9 '13 at 18:11
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    depriving a device of power and letting the caps drain is a very common practice with embedded devices, which share many similarities with desktop systems. I don't think you'll find a specific answer, but glad its working for you. – Frank Thomas Apr 9 '13 at 18:22
  • Hope it will be working in the future without problems.. – Mark Hähnel Apr 9 '13 at 18:24
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    Yeah, as Frank suggested, removing power for a duration causing a miraculous recovery typically indicates bad capacitors. I'd be ready for a dead power supply or motherboard. – LilCodger Apr 10 '13 at 23:01

The poblem is caused by improper electrical value detected by the sensor chip that locks out the motherboard startup. The solution to avoid these problems is to change power supply (500W min) and check that there are no electrolytic capacitors swollen.

If you notice any electronic component in a poor state of repair it manually because I do not recommend you always would be unstable.

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