Firing Up Your Homebuilt Computer
The moment of truth has arrived!
Before starting your computer for the first time, take a moment to check the computer parts yet again, making sure everything is properly connected and seated inside the box. Make sure the wires aren't blocking the fans. Makes sure there are no screws rattling around, and that you didn't leave any tools inside the machine.
I know, you did that already on the last page.
Otherwise, take a look on the back of the computer at the power supply. Chances are that you will see a little slider switch. Make sure that this switch is set to the correct voltage for your part of the world.
In the United States, the correct power setting will be 110 - 120 volts. In your part of the world, well, I have no idea. Ask someone local if you are unsure.
Plug the power cord into the power supply, and the other end into a surge-protected AC power source or a battery backup. Hook up the keyboard, monitor, and mouse to their appropriate connectors, and press the power button.
The CMOS Setup Screen
If you have done everything correctly, after a few seconds you will hear a delightful beep as the computer passes its very first POST (Power-On-Self-Test), and you may be greeted by a screen that looks something like the one on the right. (You may have to press DELETE, F2, or some other key to get to this screen, depending on your motherboard. Read the manual.)
If you see something that looks like the picture shown here, then pat yourself on the back. And exhale. Your homebuilt computer is alive!
What you are seeing is something called the CMOS setup screen (or the BIOS setup screen). This is all your computer is capable of doing until you install an operating system on it, and the settings you select will affect the way your OS performs. Most computers come with CMOS settings designed for Windows, so you may not need to do anything at all.
That's good for me, because there are too many BIOS versions out there for me to really guide you along at this point. You'll simply have to read the motherboard manual and follow the instruction given there (ACK!).
But here are a few basic suggestions:
Start with the default settings. You can tweak them later if you like. Just check to make sure that the time and date are correct. You can use local time or Coordinated Universal Time (Greenwich time). Most Windows machines use local time, and most Unix and Linux machines use Greenwich time; but either will work either way.
If you don't know what something means, leave it alone. Use the default settings unless you know what you are doing.
Make sure that all of your drives are showing up. If not, then shut down the machine, unplug it, and check all your drive connections and jumper settings again.
Before installing your operating system, make sure that the CD-ROM drive is set as a bootable device (unless you will be booting from a floppy for the installation, in which case make sure the floppy drive is set as a bootable device). You can usually find the settings for the boot sequence in a section of the CMOS screen called, appropriately enough, Boot Sequence.
- Make sure the date and time are correct before installing the OS. Incorrect dates and times can cause all sorts of problems.
Once you've finished CMOS setup, saved the settings, and rebooted, you're ready to install the operating system.
What if it doesn't work?
Stay calm. And don't cry. Unless you're a little kid. Then you can cry if you want.
The most common reason why a new computer doesn't work is that something isn't connected or seated properly. Here are a few very general tips about where to start looking:
If absolutely nothing happens when you push the power button, then chances are that the power supply isn't connected, the voltage switch is in the wrong position, or there is a toggle switch on the back of the power supply that is in the off position. (Check to make sure the computer is plugged into the AC power, as well. You wouldn't believe how often people forget to plug the machine in.)
If the LED's light up and the fans start turning, but nothing else happens, then most likely either the processor or the video card is not properly seated. Power down, reseat them, and try again.
If the computer begins to fire up, but then emits a shrill alarm, power down the computer and re-seat the RAM modules and peripheral cards. If that doesn't work, then check the motherboard manual to see what the alarm means. (Different combinations of beeps mean different things, but the codes are different on different motherboards, just to keep us geeks on our toes.)
Sometimes, two expansion cards sharing the same resources can prevent a computer from booting. If everything else checks out, remove all of the expansion cards except the video card, and try to boot up again. Then re-install the cards one-by-one, starting the machine after each card is installed to identify the problem card. Sometimes just moving the cards from one slot to another will make them work. Power down and unplug the computer every time you install or remove an expansion card.
Most motherboard manuals include helpful diagnostic and troubleshooting information. Consult the manual before you get depressed. Most problems are simple ones that can be easily corrected.
We hope you've enjoyed building your own computer. It's been a lot of fun for us. Now that your computer's finished, don't for forget to protect your machine from viruses and hackers, and to decide on a backup solution. It would be a shame for all your hard work to go to waste!
If you would like to see your computer-building experience documented on this site, please send an email to
Thanks for letting me help you build your own computer!
- Assembling your New Computer