My computer power light is flashing on an off. Computer won't switch on. Any advice would be great.

Might be in some type of sleep or hibernate mode

Try hitting the esc key


Any changes that either happened or that you perhaps made to your computer around the time that the problem started.

Does this happen regularly? Have you powered down your computer and restarted it? Does it happen? Is it a constant on/off blink or is there some type of distinguishable pattern? While the light is blinking, did you press the power button once to see if it would come out of hibernation?

Generally, IF the computer is not already in hibernation and the computer is doing this it's usually a sign that there's a power issue at hand and that the system is not receiving enough power to stay constant. There's a PSU test kit available for about $35-$40 that has multiple plug-ins to test voltage across the board from the PSU. It might be something worth looking into obtaining in order to help trouble shoot this issue IF the computer isn't just sitting in hibernation mode.

Is your computer a laptop? If so, you may need keep the computer plugged into the charger. You might also need a new battery.

If you computer happens to be a Dell, then the computer is hibernating. You need to hold the power button down until it turns on. Usually just a couple of seconds.

The problem may be that something happened to put your computer's power supply unit (PSU) into some protective state. It may stay in that state until you reset it by doing the following. You'll need a short (maybe 3 inch) length of electrical wire. 14 gauge solid (rather than twisted strand) wire worked for me.

1. Unplug the external power cable.
2. Open your computer and unplugging all the connections from the power supply unit (PSU) to your motherboard and other internal devices. On my computer,same connectors had tabs I had to press to allow them to be detached, while some (on the hard drive and CD drive) I just had to wiggle and pull quite hard. You'll reconnect them later, so be sure to note how to re-connect them.
3. Plug in the external power cable again,
4. If at this point the light is continuously on, rather than blinking, continue. [If it is still blinking, as far as I know, you'll need to get a new PSU.]
5. Unplug the external cord again.
6. Now you use the short length of wire I said you'd need. Use it to connect the PSU's ATX connector's green wire (the PS_ON, or soft on-off, pin) to one of it's black wires (ground). (The PSU's ATX connector is the large one that went to your motherboard. having a 2x10 to 2x12 pin connection.) Just shove one end of the wire into the green wire's hole, and the other into a black wire's hole.
7. Plug in the external power cord again. The power light should be constantly on again. You just reset the PSU.
8. Unplug the external power cord (again).
9. Take the your short length of wire out of the ATX connector.
10. Reconnect all the internal power connections that you disconnected in step 2. Close the computer.
11. Plug in the external power cord one last time. If your problem was like mine, your computer should work now.

I encountered this problem when I changed my computer's motherboard and CPU (from a 1-core CPU to a 4-core CPU). As soon as I started up the new setup, the power source unit light (next to where the power cord comes into the computer) started blinking, and otherwise the computer was completely dead. Even after putting back the old motherboard and CPU, the problem persisted, until I did the reset described above. Apparently, the new setup needed more power than my old PSU could provide, and the PSU put itself into a somewhat permanent safety state.