May 25, 2004

1:58 PM

Help! One of my computers won't turn on. [more inside]
posted by jdroth to (9 comments total)

I'm a modetately tech savvy guy. I build all of my non-Mac computers (does anyone actually build their own Macs?). Thus, the computer in question is one that I've built.

About a week ago, it simply refused to turn on. The green LED on the motherboard is active, so the power supply seems to be good, and the motherboard seems to be receiving some power. But when I click the power switch, nothing happens.

I bought a new power switch at Fry's for $3. No luck.

Does anyone have any other ideas other than "replace the motherboard"? (I can afford to replace the motherboard, no problem, but I'd really rather not, you know?) What other dead parts (CPU? RAM?) would cause a computer to simply not power-on?

Motherboard is a approx. one-year-old SOYO SY-KT400 Dragon Ultra (VIA KT400 chipset).
posted by jdroth at 1:59 PM on May 25, 2004

try replacing the power supply - just plug in one from another computer.
posted by andrew cooke at 2:04 PM on May 25, 2004

My favorite no-power jumpstart:

Hold in the power button.
Remove the power cord.
Wait ten seconds or so (still holding in the power button).
Plug in the power cord.
Release power button.

This, for some reason, "wakes up" some systems. I have no idea why.
posted by mr_crash_davis at 2:28 PM on May 25, 2004

No luck, crash. Will try a different power supply when my co-workers have left, Andrew.
posted by jdroth at 2:44 PM on May 25, 2004

if you're bored, unplug the power supply and short together the correct two pins with a paperclip to see if the power supply fan comes on. i'd tell you which colours, but i'd rather you checked yourself in case i get it wrong and you end up getting shocked... (shorting the correct two pins is what the mobo does and it should bring the power supply to life).

or is the power supply fan starting up when you press the button? i've assumed it isn't because i'm guessing you're sitting staring at a silent box...
posted by andrew cooke at 2:59 PM on May 25, 2004

Most likely it's the power supply.
posted by Civil_Disobedient at 5:11 PM on May 25, 2004

Andrew, I am sitting, staring at a silent box.

Here's another piece to the puzzle: the employ who uses this particular computer reports that it was spontaneously powering off about once per week during the past month. I've always assumed this behavior indicated failing RAM, but are there other explanations?
posted by jdroth at 7:02 PM on May 25, 2004

Open up the box and remove everything from the system board except the power connector and CPU. Take out the memory, unplug all IDE and FDD cables. Remove all Video, PCI and other cards and try to boot. You should get beep codes. If you don't, you have either a Proc problem or a MB problem. IF you get no beeps, reseat the proc. If it DOES give you beeps then start adding things back one at a time starting with memory, then video, then other PCI cards, then cables.

Powering off is a bad sign for the CPU. They usually do this when they overheat.
posted by jopreacher at 9:18 PM on May 25, 2004

Thanks for your suggestions. The problem was, indeed, a bad power supply. It's purring along now with a new one...
posted by jdroth at 11:18 AM on May 26, 2004