Stephen wrote:
On Sat, 25 Feb 2012 14:31:47 -0500, Paul wrote:

Electrolytic capacitors should not be hot to the touch.
If an electrolytic were to have reverse polarity applied to it,
it could explode. That used to be a joke in electronics lab,
to reverse an electrolytic in someone's breadboard when they
weren't looking, such that it would pop when they turned the
power on. The air around the area, is filled with filaments
of what looks like carbon deposits (like black confetti). I've
only been present for one of these "jokes", which I don't
consider to be that funny.

Now, the other kind of capacitor, is the polymer kind. The difference
is, the electrolytic has "pressure relief seams" stamped in the top
for safety. The polymer cap doesn't have pressure relief on top,
just a smooth finish. I have no idea how polymer caps behave to
polarity reversal or other insults. I've never tried to make
any blow up :-)

Hello again,

Sorry for the delay in replying to your posts. I have now bought the
GA-M68M-S2P and as this proves, it is up and running.

It is interesting what you say about capacitors. The one that was hot
had, IIRC, EC40 printed on the board next to it, so I assumed that
stood for electrolytic capacitor number 40. But now I have been
thinking about this and didn't Gigabyte do a marketing campaign where
they said they did not use electrolytic capacitors?

The capacitors on the faulty board are radial metal cylinders but the
tops don't look quite like electrolytics: they look more like metal
transistors if you can imagine what I mean.

However my replacement board has electrolytic capacitors and like you
say, these have stamps on the top (though I never knew before now what
these were for - thanks), so perhaps their budget boards still use
electrolytics or perhaps that marketing campaign has been and gone?

Thanks,
Stephen.

There is nothing wrong with electrolytic caps.

The "capacitor plague" was caused by a stolen formula for the electrolyte.
They forgot to stabilize the electrolyte, and a lot of bad capacitors were
made as a result. This caused premature failures, and even failures while
the caps were not being used. I had an Antec power supply, with very few
service hours on it, and two years after purchase, opening the lid showed
leaking capacitors. So the "chemistry error" in the construction of the
caps, can cause their demise, even without bias applied.

http://en.wikipedia.org/wiki/Capacitor_plague

To distance themselves from the capacitor plague, the major motherboard
makers switched to polymer. It was for marketing purposes. It was
a way of saying "see, I didn't buy any electrolytic capacitors of
unknown quality when I made your motherboard".

I have an 11 year old motherboard, and the electrolytics in that
are still good.

One capacitor manufacturer states, that without abusive temperatures
applied, the lifespan can be 15 years or so. Past that point, the
rubber bung in the bottom of the electrolytic, tend to dry and crack,
and then the electrolyte inside dries out. There is a big difference,
between a cap lasting 15 years, and one leaking and oozing after only
two years (stored in a closet).

Gigabyte uses different colors of polymer caps on their motherboards,
but I'm not aware of the significance. I've seen all manner of
construction styles, pure electrolytic, mixed electrolytic/polymer
(polymer where it makes sense, like VCore), as well as pure polymer.
So all the styles have been tried. It's true, that you'd expect
a better lifespan from a pure polymer board, but you can also
get just as much fun from a properly designed electrolytic board.

Paul