A friend of mine asked me to help with his Compaq Presario 5451, due to no power. When plugged into an electrical outlet, there's no power. I tried several power cords that I knew worked, but still no power. I then traced the connection from the power supply to the connection on the motherboard, which looks secure. I then tried jingling the wires a little to see if the problem might be a short in the wiring of the power supply, but still no power. Does anyone know what else could be causing this? My friend says he bought the computer 2/02, took it to a repair shop to replace the power supply for this type of problem 6 months after getting the computer (he didn't buy a warranty with it) and now it's having the exact same problem again. The power just goes out and that's it. Anyone know what else could cause this problem other than the obvious (bad power supply)?

you said you followed the connections to the motherboard. Make sure that the button or switch to turn the computer on is doing its job. You might have to do a little disecting if you know what i mean. If you have an old computer laying around throw the power supply in the compaq in the other computer and vice versa. If it is the power supply again, most likely since this would be the second power supply to be replaced in this pc i would have to say change the outlet that it was plugged into. Meaning dont plug it back into the same outlet because there could be something wrong with that outlet. I used to have an outlet in the house that would tend to burn everything. It caused a lot of frustration. But once i figured out the problem. I had it fixed and never had that problem again. If i can be of any more help email me. Good luck. Todd

Thanks for the advice. After continuing to get no where, I looked at that power connection (where the power button resides) to see what those wires looked like. There are two wires that go into the switch for the power button, but there are six possible ports these two wires could plug in to. I think the wires may not be plugged in correctly, but I'm not sure what the right configuration would be either. I tried the Compaq site, but they have no diagram for this part of the system. Any ideas out there?

New-Guy Could you give me more detail on where the Six wires off the power button are? What I mean are these six wires coming directly off the load side of the power switch or coming off the power supply? Are they multi-colored wires? Need more info to help JJK Do you have a voltmeter?

Don't have a voltmeter, unfortunately. There are only two wires going to the power button, but the power button has six connections (or possible ports) the two wires could go into. There are 3 ports on each side of the back part of the power button, with the wires connecting to the lower and middle port on the left side. There are four other wires, but they connect to the lights on the front part of the CPU cover (two to each side). I tried to find a diagram to show me exactly how these wires should be connected, but couldn't find anything to reference. Let me know if you need more to go on. Thanks for the help.

Hi, I had a similar intermittent power problem, and found the problem was the power switch on the front panel. In PCX computers this is a "momentary" switch, which sends a brief 12v signal to the mobo / power supply to start the system. This switch only needs two wires, even though there might be six prongs on it. So don't worry about that. Try replacing the switch (I found one on an ancient PC I had in the attic and it worked fine. Good luck. Felix

Thanks for the idea Felix. I'll try that this week-end when I get my hands on an older PC I can use for parts and post back with the results. Thanks again.