Now that we discarded everything that we would categorize as “silly problem” you will need to open your computer. For that you will need to remove the case left panel by removing the two screws located on the right-hand side of the computer rear panel and sliding the panel towards the rear side of the case.

Now you will need to remove everything that isn’t necessary for the computer to turn on. This is really important. To turn on the computer needs only the following components:

• Power supply;
• Motherboard;
• CPU;
• CPU cooler;
• One memory module;
• One video card.

So everything else that you might have must be removed from your computer. This includes all add-on cards you may have (e.g. add-on sound card), hard disk drives, optical disk drives, memory modules (leave just one installed), your second video card, case fans, extra fans etc. If your motherboard has on-board video and you have an add-on video card installed, remove the video card and install the video monitor cable on the on-board video connector.

Component removal must be done with no power being supplied by the power supply or you can damage components. Since your computer isn’t turning on you may find this difficult to determine. To make sure that no power is being supplied to the components, simply pull the main power cord from the wall. This is the best way to perform this procedure.

As you can see from our list above, the computer doesn’t need any disk drive to turn on. So don’t forget to remove them (you need to remove the cable that connects the drives to the motherboard AND the power cables that connect them to the power supply). You also need to disconnect the auxiliary fans present on the case from the power supply.

After removing the components that aren’t needed, try turning on your PC again (don’t forget to put the power cord back on the wall). Does it turn on now? Great, you solved the problem and now you need to install all parts back in place, one by one (i.e. turn off the computer, put one part back, turn the computer on again and see if it is still turning on). Don’t forget that you can only install components with the computer turned off, so you need to turn it off before installing the next part. If after reinstalling a part it stops turning on, this means that the last part you reinstalled is defective and must be discarded and eventually replaced or it can also be a bad contact problem with this part, which we will talk about on step four. Do not reinstall all parts at the same time, as you won’t be able to determine which component is defective. That is why we are telling you to reinstall the parts one-by-one and turning on the computer after reinstalling each part.

If your computer is still not turning on, it means that one of the parts listed above is defective or you have a bad contact problem. Before we continue, take a good look on what happens when you try to turn on your computer, this time with the case opened and with only the parts listed above installed:

• Is the power supply delivering energy? You can check this by seeing if the LEDs present on the motherboard and/or the green LED present on the case frontal panel are turning on when you press the case on/off switch. If it isn’t delivering energy this means that the power supply is defective and must be replaced.
• Is the CPU fan spinning? If it isn’t and assuming that the power supply isn’t defective, the CPU fan is defective and must be replaced. Several motherboards have a protection circuit that will shut down the system if the CPU fan is defective.
• Does the computer seem to be working for some seconds and then it shuts down (i.e. the CPU fan spins for some seconds and then the PC turns off by itself)? This can be several things but for now you should try resetting the CMOS memory (we will describe this procedure on next page).
• Can you hear any beeps coming from the small speaker located in the case? If you can, this means that you probably have a bad contact problem on your video card or memory modules (more about this later) or they are defective.