On Tue, 8 May 2018 15:23:42 -0000 (UTC), Yes
wrote:

When I turn off power completely (using the on/off button on the PSU),
wait awhile, turn back on the PSU power button, and then turn on the pc
using the on/off button on the front of the pc, I get the same problem
described above - pc lights up but immediately stops.

The problem occurred while I was troubleshooting a problem with a new HD.
My testing of the HD involved frequently turning the pc on and off in
order to switch the power cords and SATA cords among the HDDs.

My first thought was that the switch on the front of the pc broke, but
that doesn't seem likely because the pc will power up however briefly
when I press the switch.

Second thought is that there's a "fuse" ?? needing to be reset.

Third thought was wondering if the CMOS battery needs replacing.

Fourth thought was worrying if I need to replace my mobo.

Fifth thought was same question but about my PSU.

Sixth thought is wondering if I corrupted BIOS somehow. I would enter
BIOS to check if the new HD was listed in the SATA info, so I was always
entering and exiting BIOS and resuming booting up.

My notes about the pc are not handy. The mobo is an ASUS AMD mobo about
4 or 5 years old- I don't have its model number handy. The CPU, PSU, DVD/
CD device and graphics card are the same age. The HDDs vary in age, all
SATA. I have four. IIRC, the PSU is rated to handle 600W.

Thanks,

John

Another -- I didn't check if this is already mentioned -- is when
putting together a new build.

First, though, I breadboard them, conceptually rather loosely and
partially assembled on a table, for that contingency; ... maybe a
piece of cardboard under the MB between the case, the PS propped up
somewhere and such. Could then be any number of problems, although
all after the obvious: 1a, always pinjumper a BIOS reset, 1b) monitor
& keyboard, 2) barebone case to MB connections, 3) correct PS
connections -- least and last, to lack a BIOS post.

And so, once, it did so happen. I pulled the MB, out and insulated
from the case, and it powered up. Then I reinstalled the MB with
extra care to every case standoff: insulation grommets placed topside
to the male screw, and beneath, to the tapped female column post.

Fixed, although not every MB/case combo will act up like that.

On the subject of swapping a PS. They would seem to be something
along auto tires: A good idea have a spare, and easy enough, in case a
computer doesn't roll, periodically, even if for good measure, to put
one on and give it a push.

Watching -- I just bought two spare PS units, this past couple weeks,
on sale promotions. Both new: one for $12 and another $25. They're
probably back up and together around $100. Beateruppers.