I am buyilding a basic PC for my mother-in-law, and everything was going well until I tried to power up in th case today. I can only get it to post and stay on with the case power switch not connected to the mother board.
Here's the system:
CPU: Athlon II X2 255
PSU: Cooler Master 460W Elite power
Case: Cooler Master Elite 371
2x4GB DDR3 RAM
I sucessfully got a post when I had all the core components tested on the MB cardboard box.
When I installed in the case, the fans all started, the LED's came on, but then it shut down after about 5 seconds. If I unplugged the powerswtich cable from teh MB, then I can get the system to power up and get a post beep. I even got the BIOS to appear on the monitor so I could set it up to boot from the CD-ROM for a windows install.
But if I plug the little power switch cable back into the MB, then it cannot stay on and post.
I looked at the checklist and I think I have most of that covered, and I CAN get it up and running, so I don't think there's a core component problem.
So does my case have a bad power switch? It's a new case and I would think this shouldn't be so.
If the power switch is short circuited then the symptoms that you described will occur. Is the power button stuck in? It is unusual for the power button to be shorted, check the solder connections to the button. you can use a multimeter to check if the power switch is shorted.
Sounds like that switch might be faulty. If you have a multimeter with a continuity tester, (or a battery and a light globe) test to see whether it is able to break the circuit (no electrical connection) when the button is not pushed in.
If its broken, I suppose it'd be worthy of a warranty claim. Alternatively you could buy and install a small momentary push-button switch to replace it. Should only cost a dollar to buy from a radioshack (or other electronics store where you live) to replace the power button.