Re: tlug: non-Linux memory question

[Karl-Max Wagner <karlmax@example.com>]

> I'm looking to get some 72-pin SIMMs.  The old ones I'm trying to
> replace have silver traces, and I was told by a salesman at LAOX
> ComputerKAN that one shouldn't mix gold and silver.  I.e., if your
Aha, the type heard a bit about the electrochemical potentials
of metals, but has no practical idea about it.

The electrochemical potential of silver and gold are close by,
however, just 100 mV or so from each other. So there won't be a
big effect except if you run your machine under the sea....

In a computer actually you have quite a few more or less
dissimilar metals anyway, e.g. copper, solder ( an eutectic
tin/lead alloy with normally 60 % tin and 40 % lead ), Kovar
( this is what the processor pins are made of, it has the same
mechanical temperature coefficient as glass and most ceramics -
chemically it is an iron alloy with iron for the most part ).
Kovar is quite low down in the electrochemical potential against
the rest of the guys in your machine, so that's where troble
will occur first. Then the ubiquitous copper / solder joints
which have a much higher electrochemical potential difference
than silver / gold has.

However, inside a computer there's rarely enough humidity to
cause any real trouble anyway and if you fear trouble you can
use stuff to protect your contacts. Substances that are good at
that are any oils with abilities to "creep" on a surface and
pushing out any ionic liquids ( water, acids, bases and
suchlike ). Good stuff is anything based on silicone oils. There
are also specially formulated contact oils that remove any
oxides, nitrates, sulfides, metal salts etc. from the surfaces
as well. A prominent example is some stuff called "Cramolin" by
Schaefer KG here in Germany ( I tested it against pretty much
anything and nothing comes even close - they make it since the
twenties using the same secret formula ). There are also contact
sprays - just their effect lasts only a limited time - a year or
so and then it's often worse than before. What could help is
using those sprays to clean off the dirt, wash them away and
spray silicone oil on the surface - that should work longer
( however, I never tested that - I always use Cramolin.... ).
> SIMMs have gold traces, you shouldn't use them with sockets that
> are silver in color.  And vice versa.  Well, his expression was
> something like "chotto shinpai".
The only thing which is "chotto shinpai" is that he tells that
more customers without telling them the full story. There ain't
nothing as bad as half knowledge.....

Conclusion: I have quite a few computers running here and NEVER
had trouble with this. If the contacts are dirty, I just clean
them ( mostly ) with ethanol, isopropanol or suchlike and that's
it. Maybe I apply some Cramolin just to be sure - but normally I
don't anything. Dirty contacts normally only occur with
motherboard picked up from junk - never with new or normally
used ones.

Hope that answers your questions.

                                Karl-Max Wagner
                                karlmax@example.com
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