How To Turn On A Computer

This post is a how-to guide showing you all the steps to turn a computer on. A few basic computer parts must be connected correctly before you can begin.

These are the basic requirements for getting your computer to turn on. If nothing comes on, ensure all the outlets are switched on and follow the rest of this guide to ensure the best chance of success.

Note: You must also have a keyboard and mouse connected for both startup checks and to operate the computer.

How To Turn On A Computer

1. Check if your computer is connected to power

Start a computer how to tutorial. Turning on PSU rocker switch.

Make sure the power cable shown in the image is plugged in. In most cases, there is a rocker switch near the plug. Make sure it’s set to the 1 position.

Check if the lead’s other side is plugged into a power socket. Make sure the socket has been switched on.

2. Check to see if your keyboard and mouse are connected

keyboard and mouse illustration

usb connector
motherboard ps2 connectors

Follow the cables from the keyboard and mouse to see if they are connected.
These are the connections that the plugs can go into:

The two top sockets, known as PS2 ports, aren’t commonly used anymore. The two bottom sockets are known as USB connectors.

If your motherboard still has PS2 connectors, the keyboard plug is purple, and the green one is for the mouse. A USB plug looks like this:

Make sure the keyboard and mouse are plugged into the corresponding socket type.

3. Check if your monitor is connected properly

There are four common ways your monitor can be connected. Here is a list of each type to ensure the plug is inserted into the socket.

Important: Ensure the relevant plug is plugged into the computer and the monitor’s socket.

VGA Connectors

vga connector
A VGA port or socket.

VGA stands for Video Graphics Array. It’s not commonly used anymore, as it contains an analog signal.

That means that the amount of data it can display is rather limited. So the image on your screen won’t be of high-end quality.

DVI Connectors

dvi connector
dvi socket

DVI (Digital Video Interface) comes in an analog or digital version. The digital version is the superior of the two.

HDMI Connectors

hdmi plug
hdmi socket

HDMI (High-definition Multimedia Interface) is a commonly used connector for TVs and gaming consoles. It is a digital interface and provides good results.


display port plug
display port socket

DisplayPort offers good resolutions and excellent speeds.

4. Check your monitor is connected and powered up

power supply for monitor

After you have the correct display lead plugged into your computer, check to see if your monitor (screen) has electricity hooked up to it.

It may have a power brick connected to a mains cable.

In this case, ensure the barrel plug is connected to the monitor and the power cable end is connected to a mains socket and turned on.

An IEC power plug is plugged into the back of a monitor.

Connect the power cable directly to the monitor if it doesn’t have one. Plug the other end into a mains socket and turn it on. It should look like your computer’s power cable.

5. Turning the PC on by pressing the power button

A finger is pressing the power button on a desktop computer.

You are now ready to start it up. There will be a power button somewhere on the front panel. It may also be near other sockets or lights or perhaps on the top front edge of the computer.

If you aren’t sure of which one it is, press one at a time. Continue through each button you can find. Wait fifteen seconds before trying the next button.

Eventually, you will hear it start up. When it does, stop pressing the buttons immediately.

Recheck the power connector if you have cycled through each button and don’t get any lights to come on or hear anything.

Ensure it’s plugged into the back of the computer and the other end of the cable is plugged into the wall socket. 

Also, recheck the switch at the back, where the power lead plugs in. Make sure that it is in the 1 position.

Also, make sure the wall socket switch is on. If you still don’t hear or see anything happen bad news, the computer is faulty.

If it sounds like it’s started and you don’t see anything on your screen, inspect the monitor for any buttons.

Check to see if your monitor has a power button you can press. It will likely be off if you don’t see any lights on the screen.

Once you have pressed it and nothing happens, ensure it has power by rechecking your cables to the monitor.

Your monitor may be faulty if you still cannot get an image or a light.

If you have an image and your computer is running, well done! You have been successful in starting it up.

Extra Tip: A much more advanced way to turn a computer on, is to set a wake-up feature in your computer’s CMOS.

You can wake it up using your keyboard, mouse, or device plugged into a peripheral port.

For a laptop

A finger is pressing the power button on a desktop computer.

Sometimes, turning on a laptop isn’t as straightforward as pressing the power button. Occasionally, laptops can black screen or remain in a sleep state that is hard to wake up from.

So, you might need to hold the power button down first for about 20 seconds to be sure.

After that, release the button, wait five seconds, and press the button once as you normally would. If your laptop has power connected to it and/or has a full battery, it should turn on.

If it still won’t turn on, you might have something else causing startup failure, and you will need to take it to a professional to look at it.