In the fourth part of this series on troubleshooting a computer that won't turn on, we discuss problems related to video cards and displays and how to narrow down the problem and fix it.
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If Your Computer Turns On, but the Screen Remains Black
Troubleshooting video and display problems isn't particularly difficult, but it takes time and there are many steps. We'll start with the basics then work our way up from there.
1. Make sure your display (moniter, CRT, LCD, screen, whatever you prefer to call it) is plugged into a wall outlet or power strip and powered on. Also ensure that it is securely plugged into the back or bottom of your display. Many displays do not have removable power cords, making them more prone to shorts and other damage. Check your cable to make sure it isn't damaged.
2. Make sure the power strip or wall outlet that your display is plugged into are functioning by plugging another electrical device, such as a lamp, into it and switching it on.
3. Check the connection between your computer and your display. Make sure that it is completely plugged into both as well as fastened with the attached screws.
5. To double-check any possible cable problems, if at all possible, swap out the screen's power cord and the cable connecting your computer to your display.
6. Swapping out your display is also a good way of narrowing down the problem. If you get the same result with a different display, then you can be near positive the problem is something in your computer. If switching displays fixes it, then the culprit is a faulty display.
7. Try turning your display on and off. Does the power indicator light change? Green means On, amber means Standby, and no light means no power. If your display starts out green when it is turned on, then goes to amber, that usually means that it is not receiving any signal from your computer and therefore assumes it is not needed. The problem is most likely not with the moniter but in the computer.
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Problems Inside the Computer
8. The most likely is a faulty video card or video controller. If you have one handy, swapping out the graphics card is the easiest way to go. If you are using the intigrated video controller on the motherboard as opposed to a separate video card, installing a video card in the AGP or PCI-e expansion slot is easiest. Most people, though, don't have extra video cards lying around that just happen to be compatible with their PC. Before you run out to the store, lets try one more thing.
9. Occasionally, new display drivers or other manual changes to the way your video card/controller works can cause no-display errors. Another possible cause can be a problem with your CMOS or CMOS battery which causes it to lose, corrupt, or change some vital settings for your display. Or, you may have been getting creative with your PCI-e slot voltages and screwed something up. I have definitely never done that. Nope, never. Either way, blanking the CMOS settings will either fix the problem or rule it out as a factor.
Open up the case and locate the CMOS battery. It looks like a nickle and will usually be laying flat on the motherboard. Sometimes they're installed in a slot vertically. This guide may be of use to you in finding and handling the battery. Make sure the computer is unplugged and that you are grounded to avoid damage to your computer via electro-static discharge (ESD).
Reach in and pop the battery out. You'll probably need a small flat-head screwdriver to do this. You shouldn't need to force it. If you are forcing it, chances are you're going to break whatever device is holding it in there. Be careful and keep an eye out for anything that looks like it will release the battery. Most, though, will just pop out with a little pressure.
There are conflicting reports about how long you need to have the battery removed to be affective. In my experience, 30 seconds is enough, though I've heard and read as long as 30 minutes. If you want to be sure, go with 30 minutes. If you want to be reasonable, go with 30 seconds. Removing the CMOS battery makes your CMOS "forget" its settings. You will have to reconfigure the time and date, and possibly other settings for your disk drives.
Put the battery back in and close up the computer.
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If the above troubleshooting steps did not resolve your display problems, then you almost certainly have a failed video card or video controller and need a new one. This guide will help you figure out what you need to buy, and this guide will help you get it installed.
Computer Troubleshooting - If Your Computer Will Not Turn On
"HELP! My computer won't turn on!" As the owner of a PC repair shop, these are words I hear every day. Find out what the most common causes are and simple steps you can take before bringing it in for repair.