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Power Supply Issues
by chris

"Usually every morning when I power up, the monitor won't come on until I turn off and restart. Could it be the power supply?"
- Ken - Mpls MN

My first question here is whether the system is not starting up on a "cold" start or whether the monitor is not coming out of a power saving mode.

When you first power on the computer, it should go through a Power On Self Test (POST) process. During this stage, the system should be checking for responses from the primary components, including the drives, keyboard, and video. If there is a speaker connected to or on the motherboard, you should hear a short beep as the system starts up. If you see symptoms like the power and drive lights coming on, but then not going off again, your system is probably hanging-up during this POST phase. Power supply, memory and other system board level problems all could cause a system to hang before video is being displayed, although the system BIOS ultimately controls when video first appears. One of the less obvious causes might be memory, although you would normally have a video signal by this point, showing either the graphical startup "Splash Screen" or the text-based BIOS and memory count activity. If it was something like a stuck reset button, powering off and on should make no difference. Some monitors that support power save modes will display a green light when powered on and a video signal is being received, and a yellow light to indicate power, but no video signal. If your monitor supports this, with the monitor is powered on before the computer, you should see the light as yellow, then green shortly after power to the computer is applied. If the light turns green, then back to yellow, it would suggest a problem with the power supply or system board. If the light turns green, starts to display your BIOS or splash screen, but then goes blank, this would point to a startup problem in one of your other components, and not a power or video issue.

While the power supply could cause this behavior, I would not rule out something like the hard drive not spinning up or another device that is being tested during startup which is not responding. Having to shut down and restart the computer suggests an intermittent startup condition, and the hard drive would be one of the first things I would watch. If the drive access light comes on and stays on, either the system board or memory is hanging during POST or the drive itself it is probably having problems. If the drive is having problems, it may be working up to a "catastrophic" failure. (This doesn't mean that all your programs and data will go away, but if the drive won't spin up more than half the time, it's just as bad.) If the drive is causing your system to hang during POST, I would look to replace the drive before it gets any worse. You can always move the original drive to the "slave" position and use it to backup your primary drive, but I would stop using it for any critical data files after replacement.

If the monitor is not coming out of a power-saving mode, then you should be able to check this by powering the monitor on and off, and not the whole system. Generally the monitor must be powered on during the startup process for the video card to detect the device. The monitor should not come out of its power-save mode until it receives a signal from the video adapter. If the system is hanging early in the POST process, then it might not get a video signal. Some video cards will display a signal immediately on power-on as they go through their own POST process, while others do not produce a signal unless the BIOS starts displaying startup information.

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