Before doing it, connect all of the external peripherals to the system. This includes the mouse, the keyboard, and the monitor. You don't need to connect anything else yet. Besides, if you are following this procedure, you won't have these parts installed yet. 

Also, you need to have a valid system disk. The disk should include "fdisk.exe" and "format.com" along with the other necessary system files. 

1.) Stick your system disk into the A: drive. 

2.) Turn your monitor on, and let it heat up a few seconds before proceeding. 

3.) Keep in mind what to expect. You may need to act quickly. The power LED should turn on, then fans should start spinning, the hard drive should power up. You will see the video BIOS screen first, then you will see the BIOS screen and it will proceed to count the memory. You may hear one beep from the PC speaker. You may also get a "CMOS checksum error" or another error saying the CMOS or time isn't set. Know what key(s) to hit to enter setup. This will be shown on the bottom of the screen. You will want to do this quickly. If you hear any weird sounds such as grinding, scraping, or loud whining, be ready to turn the system off immediately. 

4.) Press the power switch. If it powers up, observe the system closely. As soon as the BIOS screen appears, press the appropriate key(s) and enter BIOS setup. The correct key combination should be visible at the bottom of the screen. Sometimes it pops by too quickly for you to see which keys to press. No problem. Don't hesitate to just hit reset and try again. A lot of times, the Delete key will do the trick. 

5.) If things didn't go according to plan, troubleshoot the system. Walk mentally through the boot process and check all hardware as it goes. Think like the computer thinks, if you know what I mean. One common thing I see with ATX machines is that people press the power switch and nothing happens. Usually this is due to the fact that the power switch is either not connected to the motherboard or it is off by a pair of pins or so. Just make sure that it is connected properly to the right pins. Makes sure the master power switch on the rear of the power supply is "on". If you rule out everything, you may need to unscrew the motherboard and put in washers. Somewhere, you may have inadvertently grounded the board to the case, causing it to not power up. 


Note: If it powers up, but you get no video or a series of beep codes, then you need to troubleshoot something else. Consult your motherboard's manual. You can also check out the troubleshooting section of PC Mechanic for some helpful data and beep codes.