"Speaker For PC Interanal BIOS Computer Motherboard Mini Onboard Case
Buzzer Board Beep Alarm NEW."

https://www.newegg.com/p/pl?d=Speake...ep+Alarm+NE W.

This is a cheap option that can be added post hoc. Is it worth it?
Maybe.

Oh ****. Restored POWER LED connectors+/- to original position. Now POWER
LED does not work. I thought these were protected by some 'magic'
circuit.

Is cheap option above worth it, pre hoc? I guess.

Indicator LEDs have a 5V Peak Inverse Volts rating.
Indicator LEDs are red,yellow,green and T13/4 size.
And $0.20 a piece, leaves some profit for the seller
(even though back in the day, RadioShack might want $3.00).

https://www.superbrightleds.com/more...ngle/285/1212/

Continuous Forward Current 30 mA
Reverse Voltage 5V === perfect for computer cases
:-)

There are some LEDs, particularly power LEDs that'll
knock an eyeball out, that those are *not* rated for
reversal. If you reverse them, sometimes they reward
you later with reduced light output, or they blow
out completely.

And some power LEDs, you can see an element next to the
substrate with the LED, and that appears to be a
reverse polarity and/or ESD protector.

Summary:

1) When around PC cases and computer motherboards,
the usage of LEDs here is "carefree". No worries
that I've ever seen, due to the 5V PIV rating of
these LED types. The motherboard always has a series
resistor, so the computer case side doesn't need a
resistor to be present.

Sometimes the wire bond fails, and this can be
caused by stress on a leg, pulling on the anvil
and maybe the wire bond wasn't properly formed.
A little chip of GaAs material is mounted on an
anvil, and a wire bond to the surface provides the
second connection to the LED.

2) When dealing with $20 LEDs from Newark, I'm a lot
more careful. I check check and recheck the polarity.

Examples of running power LEDs off a constant current source.
Sometimes the "star" hexagonal substrate, has polarity
markings. You buy them mounted this way, to avoid damaging
them by applying too much soldering iron heat directly
to the LED. Two of these light my kitchen right now :-)
You point them at the ceiling for "bounce" lighting.


http://lednique.com/wp/wp-content/up...wer-supply.png


https://cdn.instructables.com/ORIG/F...O9FDYPTCX6.jpg

Paul

Thanks Paul, I acquired a beep speaker with solid connector that connected
to pins 20, 14. Beep code "Continuous short beeps: Power error". I am
surprised. I have a NEW 400W PSU. Maybe old is better. I tested +5V which
peaks then falls perhaps due to Smart Power management Catch 22 coming from
the BIOS. I have a 5V power pack for my cell. Do you think it would be a
good idea to plug it into a USB port and see if it can power the MOBO + one
notch PCI VGA + one 500 MB DDR2-533 RAM module?

I hate suicide.