How to Troubleshoot a Desktop Computer
Most desktop faults come down to power, a cable, or Windows. These checks are safe to do yourself and need no tools. Do not open the power supply.
The computer will not turn on
- Check that the power cable is pushed fully into the computer and the wall outlet.
- If it is on a power strip, check the strip is switched on, then try a wall outlet directly.
- Look for a rocker switch on the back of the computer, near the power cable, and make sure it is on.
- Unplug everything except power, monitor, keyboard and mouse, and try again.
- Press the power button and listen: fans, beeps or lights tell us a lot, so note what you hear and see.
When to stop: Call if there is no sign of life at all, a burning smell, or a pattern of beeps.
It turns on but the screen stays black
- Check that the monitor has power and its light is on.
- Check both ends of the monitor cable, and that it is plugged into the graphics card if the computer has one.
- Use the monitor’s input button to select the right input (HDMI, DisplayPort).
- Try a different cable, or a different monitor or TV if you have one.
When to stop: Call if the computer beeps, or a second monitor also stays black.
Windows will not start
- Unplug any USB drives and memory cards, then restart.
- If Windows starts its automatic repair, let it finish once.
- If you can reach the sign-in screen, hold Shift while choosing Restart to open the recovery options, then try Startup Repair.
- If it starts in Safe Mode but not normally, a recent driver or program is the likely cause: uninstall what was added last.
When to stop: Stop and call if you see “no bootable device”, a disk error, or a hard drive warning. Those point to the drive, and more restarts can cost you files.
It is running very slowly
- Restart, if it has been on for days.
- Press Ctrl+Shift+Esc to open Task Manager and see what is using the processor, memory and disk.
- Check free space on the main drive: keep at least 15 percent free.
- Install pending Windows updates, then restart.
- Run a full scan in Windows Security.
- In Task Manager, open Startup apps and turn off what you do not need.
When to stop: Call if the disk sits at 100 percent for minutes at a time, or you hear the drive working hard. A failing drive often shows up as slowness first.
No internet
- Check whether other devices have internet. If none do, the problem is the router or the provider.
- Unplug the modem and router for 30 seconds, plug them back in, and wait two minutes.
- Check the network cable at both ends, or reconnect to Wi-Fi.
- In Windows, open Settings, then Network & internet, and run the network troubleshooter.
When to stop: Call if only this computer is affected after all of the above.
Questions
Is it safe to open a desktop computer?
Unplug it first, and never open the power supply itself. If you are not comfortable, stop and call.
Will these steps delete anything?
No. None of these steps erase files.
The computer beeps when I turn it on. What does that mean?
Beep patterns are codes, usually for memory or the motherboard. Note the pattern and tell us.
Still not working?
Call us or book online and tell us the make, the model and what is going wrong. For IT support a technician comes to your home or office. For a repair we pick the computer up from your door, fix it at our own workshop in Burbank and bring it back. We have no storefront, so there is nowhere to drop a machine off. Outside our area, you can mail it to us.