Why won't my computer POST?

There are a number of reasons why a computer will power up but not POST. Follow these steps for troubleshooting:

1. CHECK/RESEAT ALL COMPONENT CONNECTIONS

If you recently added new internal hardware, such as more memory, it’s possible that a component is seated incorrectly in its slot or that you bumped another component or cable, loosening its connection. It’s also possible that the new component is either broken or incompatible with the PC. Start by turning off and unplugging the computer, grounding yourself by touching a metal part on the outside of the PC’s case or using an ESD (electrostatic discharge) wrist strap and then opening the case. Once inside, remove any recently attached or installed hardware.

Ensure that each internal card and RAM module is properly seated by gently and evenly pressing along the length of the card or module. If it doesn’t seem to move when you apply pressure but you still feel uncertain about the seating, remove the card or module entirely, and reseat it again.

Check that all the internal cables are connected properly. If any data cable seems the slightest bit loose, disconnect and reconnect it. Make sure all power connectors are also securely attached to the motherboard. Your computer has a 20 or 24 pin main power connector. It may also have a 4 or 8 pin connector. Remove each and reattach. Be sure all your other hardware devices requiring power connections are also securely seated, including HD, optical, floppy, and media reader drives, video cards, tuners, fans, etc.

Try again to start your computer. If no success, continue to step 2.

2. CLEAR CMOS

This is a simple process, but you may need to refer to your motherboard manual for assistance in locating the CMOS battery and BIOS configuration jumper locations.

• Remove the power cord from the PSU at the rear of the computer, and take off the PC's side panel to gain access to the inside of the system.
• Remove the CMOS battery. This is normally a coin-cell style lithium battery, type CR-2032, that looks like a large watch battery.
• Move the CMOS jumper (sometimes referred to as the BIOS configuration jumper) to the clear or reset position. Wait 60 seconds (some motherboards only require 5 or 10)
• Finally, return the jumper to the original position, the CMOS battery to it's socket, and the power cord to the power supply.
• Try again to start your computer. If no success, continue to step 3.

If the computer now POSTs, enter the system setup program (BIOS) to load setup defaults, then press F10 to save changes and exit.

3. MINIMIZE SYSTEM HARDWARE

• Strip the system down to the core components (the CPU with its heatsink and fan, a single memory module in the slot closest to the CPU, a single video card, and of course the motherboard and power supply.) Disconnect the optical and hard drives from their respective data and power cables and remove other add-in cards including sound, wireless, modem, etc.
• Disconnect any external device including mouse, keyboard, external Hard Drives, MP3 player, printer, speakers, microphone, network cables, etc.
• Try again to start your computer.

If the computer now POSTs, reattach components one at a time until the determination of the faulting component is made. If the computer continues to fail to POST, try an alternate memory module. If it continues to fail to post, try a second video card.

If the computer still does not post, the motherboard may be defective. If there were not multiple sticks of memory or video cards available for the diagnostic, the problem may lie with one of those two components.