assembling a new pc

[tontod]

I am trying to assemble a new pc. I have the mobo, cpu and memory installed. Every time I plug in the power supply, the cpu fan turns on. Pressing the power switch has no effect, i.e. computer does not shut off. What I then did is I cleared the CMOS. Now, when I plug in the pc, the mobo LED comes on, but the cpu fan does not and after I depress the power switch, the cpu fan spins, however when I release the power switch, the cpu fan turns off. In other words, the cpu fan will only spin as long as I keep the power switch on the front depressed. Is it a sticky switch or a faulty power supply? The mobo is Asus A7S333.

 

[rcomo]

It doesn't sound like a faulty PSU to me. Did you check all your connections into the mobo? if (perhaps like I ALWAYS do) you have a + in the wrong spot, of maybe the connections switched on the on/off switch, you might just have a short somewhere...my noob exp anyway.

 

[mechBgon]

Try this: unplug the case's power-button wire from the motherboard. Now use a metal object like a screwdriver tip, and make momentary electrical contact between the pins that the case's power-button wire was on. The system should start running and remain running.

If it doesn't, look at the case from the rear and see if the springy finger things on the I/O sheild are sneaking into your USB or network jacks.

If that wasn't the issue, next peel the motherboard out of the case, lay it on cardboard equipped with just the essentials (video, cpu/heatsink/fan, memory, keyboard) and try the same procedure again, to eliminate the case as a variable.

 

[tontod]

If I short the 2 power switch pins with a screwdriver, the system powers on and stays on.

 

[mechBgon]

Then it sounds like your case's power-button is mechanically troubled somehow. 🙁 Try this next: plug the case's power-button wire back onto the motherboard, but take the plastic bezel off of the front of the case. Now see if the system behaves normally with the bezel off. The bezel usually has a big plastic button that actuates the actual switch on the case, and with the bezel out of the picture, you can determine if the case's power-button switch is electrically "stuck" in the "pushed" position. If it is, it's warranty time for the case.

 

[imported_raybay]

You have something hooked up incorrectly. This is definitely not a power supply issue. Go back through and check the seating of every component. Look for fan plugs that are no longer snug, pci devices a bit off kelter, bent pins on cpu or powered devices. Remove everything except one memory module, power supply, and floppy boot disk.... see if it will work with just the fundamentals.

 

[ROJAS]

Sometimes the atx plug at the end of the power supply, sometimes a pin might not be in all the way. Take a look to see if all the pins are in all the way.