uh oh... power supply or mobo?
 

so i come home one day and try and boot up my home linux box, and nothing happens. Fans power up, hard drive starts whirring, but no display. Uh oh I say. Time for the usual battery of tests to see what isn't working, but nothing helps. So it's down to this:

I've yanked everything out, leaving just memory (which I know is good), mobo/cpu, power supply, speaker. Power up, no beep. I'm trying to avoid buying a new mobo if it's not the mobo, but I don't have another power supply to test. So, I powered up the PS and hook up the voltmeter to check pins. All are normal or a little high (5V pin runs at 5.3V, etc), except that the +12V DC pin is at +11.3V and the -12V pin is at -10.8V.

Is that low voltage normal? If so, it's time to go mobo shopping. If not, power supply shopping. Any thoughts would make me very happy. Thanks!

Low voltages are normaly not a problem......

I have seen mainboards not booting like you describe (everything runing, spinning but no boot/beep) with a new amd64 or sempron system which require the aditional 4 pin powersuply connector.

Remeber that no beep at boot can mean:
- no boot
- broken speaker :-))

So your mobo is broken, or your speaker _and_ your graphicscard is broken at the same time....

(though it looks like a broken mobo to me, sorry)

I have a AGP card in mine that If I bump the case between starts it will hang cause this cheap case I have lets the card move.

yeah, i was hoping broken speaker, so i did a couple things to try that-

1. pulled apart an old phone, yanked out the speaker from the earpiece and rigged that up- no go. It clicks when the the power is first turned on, and when the power is turned off, but so does the case speaker.

2. thinking maybe there isn't enough power to drive the phone speaker (which actually looks surprisingly hefty) i tossed on a voltmeter- a quick 2V spike the instant power is turned on, and a similar 2V spike when power is turned off, but not long enough for a beep (that 2V spike is what's making the click).

oh well, i guess it's time to go mobo shopping. Thanks!

If the original problem was just that the monitor did not come on, but the disks, fans, etc, seemed to be operating normally, then the first things I'd look at would be that the monitor was turned on, and that the video cable connection was securely fastened to your video card.

Maybe I'm just misinterpreting your comments, but to be honest is sounds like both your power unit and your box seem to be operating normally. If nothing happened when you powered on, then Yes, there are some fundamental problems with your system, but if the box seems to be behaving normally but the monitor doesn't come on, I'd suggest taking a closer look at the monitor. Good luck with it either way -- J.W.

sometimes a quick flash of the cmos helps, you can do this with a jumper or just yank the battery out with the power unpluged and then put the battery back in and fire it up. You didn't answer if you video card was AGP or PCI or onboard.

sorry for letting this thread die, just wanted to tack on a thank-you to all posts.

I have both PCI and AGP cards, neither was working. Without even a beep at startup I knew it wasn't the monitor. Turns out the CPU was dead (that one really surprised me). I borrowed a friends mobo and still no luck. Bought a new CPU and everything is happy again. Thanks again.