Lee Computer Services : freelance computer/web services

Repair News Articles from the Tech Industry

March 26, 2009

Ten things to check on a non-booting PC

In my case, the computer would appear to start up -- fans firing up, lights turning, hard disks spinning up -- but the fan on top of the CPU would move slightly, then stop. There was no video signal to my LCD monitor, but the status light on the video card was lit.

What follows are the steps I took to fix the problem, roughly in order.

• Check your connections. Yes, this is the build-your-own-PC equivalent of the tech support drone asking if your computer is plugged in, only in this case, you're the drone. There are many different connections that jack into a PC's motherboard. Make sure they're all plugged in correctly, particularly those for power and fans. While it wound up not being the issue, I had missed a secondary power connection -- a four-pin plug that connects to the motherboard. In addition, pay close attention to the connections for the power and reset buttons, as well as the power and hard-disk activity lights. Plugging those in wrong could cause boot problems as well.

• Check your RAM. Check to make sure your memory modules are inserted completely. When properly installed, RAM modules make a satisfying "click" as the clips on either side snap into place. Check those clips to ensure they're in the full, upright and locked position. Also, make sure the RAM modules are in the right place -- if you have more than one stick of memory, they must be in specific slots. They're usually color-coded, but check your motherboard manual for details.

• Check your add-in cards. Make sure your PCI and PCI-Express cards are pushed fully into their slots. This is particularly true of the video card. If it's not seated properly, the computer won't boot. If you have a spare video card that you know works, try installing it. If the computer boots, the video card you initially used is defective.

• Reset the BIOS. Find the CMOS battery on the motherboard - it will look like an oversized watch battery - and remove it. Wait about 5-10 minutes, then replace it and try booting your computer. Most motherboards also have a jumper that, when shorted with a small screwdriver, will reset the BIOS. However, I'd suggest using the battery-removal method - it's a little safer.

• Swap out the memory. Of the components that can go bad in a computer, RAM is the most frequent culprit. If you have more than one memory module, it's unlikely that both are defective. Remove all but one, and see if the computer will start. If it does, you know one of the others is likely bad. Keep swapping them out until the computer won't boot again, and you've found the villain. However, if it won't start regardless of which stick is in place, you've either got more than one defective module - highly unlikely - or the problem lies elsewhere. One other option: Try using different RAM that's compatible with the motherboard, if you have spares available.

• Remove the motherboard from the case. Most cases are made of metal, and it's possible that some component on the underside of the motherboard may be touching it, causing a short. Disconnect all the connections, pull the add-in cards and remove the screws holding the motherboard down. Place the motherboard on a non-conductive surface (such as the box the motherboard came in) and reinstall just the video card. Connect the power and the monitor cable. Use a small screwdriver to short the jumpers to which you'd connect the power button. If the system finally boots, you know the motherboard is making contact with the case in a way it shouldn't. If it doesn't boot, continue to the next step.

• Reinstall the CPU. Though it's difficult for modern processors to be inserted improperly into their sockets, it can happen. Now that the motherboard is out of the case, this delicate procedure will be a little easier. Carefully remove the heat sink/fan combination (see your processor's installation instructions for doing this). Next, lift the lever that releases the bracket holding the processor in its socket. Inspect the pins to make sure that none are bent (they'll either be underneath the processor, or in the socket). If everything looks fine, use isopropyl alcohol to clean the thermal grease that was placed between the heat sink and the processor. You'll need to replace the thermal grease (a good tutorial for doing so is here) before you reinstall the processor. Follow the instructions in the motherboard and/or CPU manual for installing the processor. Once it's back in place, try starting the computer again.

• Try a different power supply. If you have an extra power supply that supports the system's voltage requirements and works with the motherboard, hook it up and try it out. If you have access to a voltmeter, you can also test to make sure the power supply is outputting the correct voltage. However, be safe: If you aren't sure how to do this, then don't. Get help from someone who knows how to use this equipment.

• Trade out the CPU or the motherboard. If you have access to an extra processor that will fit in the socket, try installing it. Alternatively, if you have a another motherboard that will work with the processor, test with that. Intel was kind enough to send me a test Core 2 Quad Q8200 to try, and that's how I was able to determine that my issue was a defective CPU. If the system still won't boot, then you'll know the component you didn't replace is likely the culprit.

Of course, if you don't have this option, you'll probably have to either a.) take a chance and return one of them, hoping it's the correctly defective part, or b.) return both the CPU and motherboard at once. This is one instance when it helps to buy a motherboard/CPU combo from the same source. This makes it easier to return both and get an exchange of the same model for each. Had I not had help from Intel, I would have chosen option B.

more... »


Valid XHTML 1.0 Strict