# mainframes and other stuff

Göran Axelsson axelsson at acc.umu.se
Wed Nov 26 05:55:27 CST 2014

```You got it right at the first time, the myth of 1+ g gold per ppro is
kept alive by eBay sellers that sells to less informed buyers.

PPros is closer to 1/3 of a gram Au per CPU (might vary up and down a
bit depending on which CPU / cache combo. Most of the gold is in the
bond wires and the solder holding the chips on place (a silicon-gold
braze ).
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=60&t=15269&hilit=pentium+pro#p154921

I'm a gold refiner / scrapper / classic computer collector, all on a
hobby basis, so my workshop is fast filling up with computers that I'm
not allowed to refine.
... there's some mixed feelings there.

:-D

Göran

William Donzelli skrev den 2014-11-25 07:18:
> Oops, I am a bit too tired, and something was bugging me about your
> calculations.
>
> PPros have more than a third of a gram - they are closer to a gram per unit.
>
>
> --
> Will
>
> On Tue, Nov 25, 2014 at 1:08 AM, William Donzelli <wdonzelli at gmail.com> wrote:
>>> Let's say that a Pentium Pro has a third of a gram; a troy ounce is
>>> 31.1 grams; so 94 Pentium Pro to the troy ounce; 4.5 pounds is about
>>> 65 troy ounces; so 6,182 Pentium Pro might have that much gold.
>> There are 12 troy ounces to the pound, not 16.
>>
>> Anyway, yes, you are talking about something like 4800 PPros
>> equivalent. Now compare the plated surface areas of a PPro compared to
>> a number of the pins on the backplane - you will find that a gold
>> plate area on a PPro (mind you, there is a fair amount under the
>> cover, too) equates to a surprisingly small amount of old IBM
>> backplane pins. Remember, the pins are long, and plated on four sides
>> - and probably had a thicker plate that on PPros.
>>
>> And yes, the 75 was a really huge machine. Gold on the backplanes,
>> gold on the connectors (early Bus&Tags have a very heavy plate), gold
>> in transistors. I would not be surprised if there was gold in the lamp
>> sockets.
>>
>> --
>> Will

```