Re: Motherboard cannot turn on the PSU

Many would consider a value of 4.85 at OK. That would be
too low and could indicate a problem with power supply.
Around 5.03 means power supply is good. The other half of
that control system is therefore suspect - on motherboard.

Once started, the motherboard circuits could be a full +5
volts from the +5 supply line. This would explain why the
power supply controller cannot turn power supply on but works
OK once +5V is obtained from another source. By process of
elimination, motherboard based power supply controller circuit
is the only remaining suspect.

Appreciate why I could not provide an answer on a subjective
"+5VSB looks OK". Without the specific number, I still did
not know if +5VSB was OK. Numbers from a meter are also
required for voltages on red, yellow, and orange wires to
confirm power supply is not telling motherboard controller to
'shut down due to a bad voltage'. Also that message of bad
power would be seen on gray wire - power good declared some
seconds later when the gray wire rises to over 2.4 volts.

If power supply does not tell motherboard controler that
voltages are OK after a few seconds, then motherboard
controller will shutdown power supply. Meter can display
that.

One need not buy a supply to test. One uses the meter to
either prove a supply fully sufficient or define that supply
as insufficient. Two minutes with numbers from critical
voltages could say, "Power supply is good. Move on to other
usual suspects." A definitive answer without speculation.

C wrote:
> I checked it again some days ago and it was around 5.03V (I don´t
> remember the exact voltage but the value is over 5V and very close to
> those 5V). I will post the exact value as soon as possible.
>
> what are you guessing, w_tom?
>
> In 3-4 days I will receive a new PSU (it is an 380W antec PSU, with my
> new case, Antec Sonata). I think it is powerful enough for my PC (XP
> 2800+, FX5200, DVD burner and ATA 160Gb HD). If the problem is in
> that voltage my mobo should work with this PSU.
.

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