On Mon, 03 Jun 2019 14:48:43 -0400, Paul wrote:

https://www.badcaps.net/forum/showthread.php?t=2265

The board doesn't have an ATX12V 2x2 power connector, with
the two yellow wires and two black wires.

That means the *CPU* runs off +5V, as well as lots of
other logic. It's natural for such an unbalanced load
situation (only an amp or two load on +12V, but
15 amps off the +5V), for the +5V to be a little
on the low side.

This is called "cross-regulation". There is only one
feedback loop in the ATX power supply for regulation.
What you'd find is, the +5V resting at its low limit,
and the +12V "higher than normal". If an ATX supply is
"non-compliant to crossloading", then the +5V could
even be too low and out-of-spec.

These are examples of ATX specs, of various generations.
The 1.1 version was back when power supplies still had a
-5V rail. The pin on the main connector is missing on
modern supplies, where the =5V pin used to be located.


Mine has -5v, a 20/24 main connector, a 4 pin +12v, and 34a on the +5v.
With a loud pop, it blew a capacitor the first time I powered it on, but
after replacing the failed cap, it works. It was a smaller cap, not one
of the two big ones. They scare me. I would throw it out if they blew.


+5VDC ±5% +4.75 +5.00 +5.25 Volts

I see 4.75v on a USB header pin. It's within spec, just barely.


You're doing just fine. Relax and enjoy your machine,
until that Athlon cooks out and smokes.

I have an Athlon that went into thermal runaway once. Don't know what
caused it. The machine froze, and the CPU heatsink burned my finger when
I touched it, like a hot burner on a stove.

After cooling down, it's run fine ever since. I never leave it running
when I'm gone though. I'm afraid it could happen again, catch fire, and
burn the house down.