Help me Obi-wan...you're my only hope

[Nickand5]

I do not know what else I can do. I built my first computer about 3 years ago and came home one day to find it shut off. When I tried to power it up, the CPU and case fans would start to turn and within 5 seconds everything would power down. I send the PSU back (still under warranty) for a new one with no change in results. Since then I have replaced my graphics card, RAM, sound card and was still experiencing the same immediate shut down. With nothing working, I finally broke down and bought a new processor, motherboard, and coordinating RAM. Last night, I put everything together and excitedly turned on the power switch only to experience the same exact immediate shut down. I cleared the CMOS and tried again. Nothing. I do not know what else to do. The case and the CPU fan are the only things I have not replaced. Is it possible one of these is my problem? Any help would be greatly appreciated as I am completely out of thoughts or ideas and ready to buy a prebuilt system!!!

Thanks,
Nick

 

[Guest]

The case and the CPU fan are the only things I have not replaced.

Does it beep at all before shutting down?

You say about 5 seconds before shutting down, this could indicate a faulty on/off switch. The on/off switch is only supposed to give a momentary power signal to the supply to turn on. If it stays in a permanent "on" mode it will invoke the master shut down sequence which is about 4 seconds - remarkably similar to your power down time.

If you can get hold of a multimeter or short circuit tester disconnect power from your PC, unplug switch from motherboard (work out which 2 wires are used for the ON/OFF function (should be detailed in MB manual). Apply test equipment to wires and operate switch, when pressed should show short when let go should clear short. If short does not clear then that is your problem.

If you can't get test equipment and you are very very careful (do this at your own risk) disconnect power from PC, find out which wires from switch to motherboard turn on PC. Disconnect one of them and carefully pull to one side ensuring it does not touch anything else. Re-apply power to PC and CAREFULLY touch loose wire to its pin for a second or two then remove (this is only a 12V signal not 230V). Assuming you have selected correct wire and touch pin correctly PC should start. If it does and continues to run switch is faulty, if it does and still shuts down then I'm not sure what else it could be.

 

[Nickand5]

I have tried something similar, I placed the old motherboard on its box, connected the power supply and used a screwdriver to touch the poser switch pins on the motherboard. Again it started but shut down right away. I do not get any system beeps with either motherboard, so ... I am not sure if it is a fault anywhere or not.

 

[Guest]

Here's a couple of options to try, I'm sure you've tried some if not all of them.

Have you tried booting up without any storage attached?

Tried pressing F8 at boot up, if you haven't and it works there should be an option like "don't restart on error" or you could try safe mode.

Tried booting from CD.

Good luck

 

[Nickand5]

I cannot even get that far into it. It really does restart within five seconds. I get fans starting to spin, a slight hard drive noise and then nothing. I have tried booting with just the mobo, fan, and ram with the same results.