[mdlug] After power outage desktop won't boot.

[Steve Litt]

On Fri, 29 Apr 2016 02:38:35 -0400
Jim Fulner <jim.fulner at member.fsf.org> wrote:

> While I was at work today it looks like my power went out at home. 
> 
> No biggie, just boot the desktop up again. And it didn't. Monitor
> flickers on, then nothing, my first attempt I heard a strange noise
> from the case that I thought was the hard drive trying to spin,
> though I wasn't sure. My 3 year old broke my DVD drive like a year
> ago so that could have been the noise, not sure. Opened the case,
> fans were spining though not really how I thought they did. Tried
> disconnecting and reconnecting things no apparent change.
> 
> I'm not really a hardware guy, what's my next step from here? A new
> PC wasn't really in the budget for this year. Would anyone be
> interested in helping me tinker with it if I bring it to Penguicon?

Hi Jim,

This is either hardware or software. Try booting a known good live CD,
remembering to hit the proper keys during POST so that it boots from
the CDROM/DVD drive. If it boots from CD, suspect something with the
hard disks or their controllers, or corruption within the filesystems.

If it won't boot from CD, see if it gets as far as counting memory. To
do that, you need to change the BIOS so that it doesn't "quick boot" or
"silent boot" and it doesn't present a splash screen. If it counts
memory, suspect disk problems.

If it won't count RAM, the idiomatic investigation technique is to
remove everything from the mobo except CPU, RAM, video card, and power
supply, and try booting again. I mean *everything*, including those
little wires from LEDs and power and reset switches, which are known
to frequently go intermittent. If *now* it counts memory, one of the
things you disconnected is at fault, so reconnect one at a time and
reboot each time until you can toggle the boot failure by
connecting/disconnecting a specific component.

If it didn't count RAM in the preceding paragraph, you've narrowed it
down to mobo, CPU, RAM, video card, or power supply. If you have
multiple RAM sticks, remove all but one and power up again. Repeat for
each stick. If the failure happens for some sticks and not others, the
sticks producing failure are bad: Replace.

If none of the sticks produced memory count, it's probably not RAM. Most
people have spare known-good power supplies hanging around. Disconnect
the current power supply without unmounting it from the case, and
connect a known-good power supply without mounting it to the case. If
it now counts memory, you had a bad power supply.

If it's still not counting memory, you have a bad video card, a bad
mobo, or a bad CPU. Swap the video card. This is easy if you already
had a video daughtercard, or very difficult if you had an onboard video
card. Difficult, because you have a buried shovel: If only you could
see, you could disable the broken onboard so the new daughtercard could
shine through, and if you could disable the broken onboard, you could
see. A lot of time, you can get past this with sufficient fiddling
around.

If swapping the video card didn't fix it, you have a bad mobo or CPU,
and personally, I consider these a package deal. Look for swollen
capacitor tops. Just for fun, replace the coin battery. Make sure the
heat sink fan is spinning. When I've narrowed it to mobo and CPU, and
there's no likely simple cause for them to be malfunctioning, I usually
buy a new computer.

SteveT

Steve Litt 
April 2016 featured book: Rapid Learning for the 21st Century
http://www.troubleshooters.com/rl21