# Pentium Pro value question



## cejohnsonsr (Jan 26, 2013)

I may have made a mistake today. I had a chance to buy an old Pentium Pro CPU at a flea market. The guy only had 1. He wanted $15. I passed. Should I have bought it? Thanks. Ed


----------



## mjgraham (Jan 26, 2013)

I know this has been asked a million times on here, but I think even some of the best refiners on here are getting about 0.3g out of them so I'd say you did OK passing if you were going to self refine, if you wanted to sell it on eBay you should have got it.


----------



## NobleMetalWorks (Jan 27, 2013)

The yield should be right around .33. You might get a little more or less, but generally speaking the yield on Pentium Pros is right around .33 on the ceramic package. Obviously if you are talking about the plastic package, the yield is much less.

On one Pentium Pro, at $15 dollars, you are not leaving enough room for any profit. On a small scale, considering the cost of acids, equipment, time, effort, energy, labor etc you are actually loosing money. I very recently processed 180+ PPs and honestly paid under $5.00 each. At the time, the actual value after being refined was right around $17.00. If I paid $15.00 each that would have been a $2.00 profit on each CPU, which would have been $360.00 which is nothing to shake a stick at, but once you figure in the propane and the labor/time to remove the caps from the bottom, then the electricity to run the ball mill, then the cost of the acids for base metal digestion (to remove the tin and other base metals) then the AR digestion, the cost of the filters to separate the solution from the ceramic material, the time effort and energy involved in that, the cost of the chemicals to precipitate the Au, then the washing, drying, incinerating, second refining digestion in AR, the washing, drying, roasting, then the cost of melting that into a button plus the wear and tear on equipment and all the other things I have not thought of to post in the processing of the CPUs, you start to realize that the $360.00 profit margin we were talking about before, has shrunk to virtually nothing.

If you are planning on making a profit, you cannot pay $15.00 per CPU and realistically make any profit at all. If you are a hobbyist refiner that is only looking to accumulate gold, and don't mind the total cost being right around spot, then it's not a bad deal I guess.

But don't feel bad passing up a single CPU at $15.00 you probably would have only made $2.00. I know there is a list floating around that claims each chip contains 1 gram, but that is simply not true, it's a total fabrication and utterly misleading. I would wager it was someone who took a yield document, added the 1 gram per CPU number, then referred to that document in an ebay listing. I have seen it before, and we will see it again, and again. So long as people refuse to record the actual yields themselves, and rely on documents to tell them the yields, there will continue to be people who pay far more than the actual value of these chips.

Scott


----------



## gold4mike (Jan 28, 2013)

The last few Pentium Pro's I had I listed on eBay and sold for about $30.00 each. I'm only able to recover about $20.00 worth of gold from one so I always list them. 

At $15.00 you could do OK. You would have a bit less than $4.00 in eBay and PayPal fees to sell it, leaving a $10 - $11 profit.


----------



## Alentia (Mar 6, 2013)

Guys, i have posted that in different thread.

P-Pro 256K Cache - 0.25gr
P-Pro 512K Cache - 0.5gr
P-Pro 1Mb Cache - 1gr


----------



## Pikachu2000 (Mar 6, 2013)

Is that really grains or is it grams? 

gr = grains
g = grams


----------



## ericrm (Mar 6, 2013)

Alentia said:


> Guys, i have posted that in different thread.
> 
> P-Pro 256K Cache - 0.25gr
> P-Pro 512K Cache - 0.5gr
> P-Pro 1Mb Cache - 1gr



alentia did you actually recovered from a 1mb cache? last time i read your post you only had done 256 and 512


----------



## Alentia (Mar 6, 2013)

It is grams.

Eric, I have not, but based on 1Mb dual 512K Cache design it should be 1gram.


----------



## goldsilverpro (Mar 7, 2013)

Alentia,

I have never processed PP's and may not know what I'm talking about. However, it seems erroneous to assume that the 1M would contain twice as much gold as the 512K. I would assume the circuits themselves contain no gold. The bottom of the chip would be gold coated if it's attached with Au/Si braze. It seems that, as in all other CPUs I've seen, the gold content is related to the packaging and not the chip (die, circuit) itself. The packaging of the 1M is totally different that the other two. The number of pins is the same (387) on all 3 sizes.

In order for the 512K to have twice as much gold as the 256K, the gold plated surface areas and the chips (if attached with Au/Si braze) would have to be twice as large. Is that true? The same with the 1M vs the 512K.

Here's a Wiki quote on the packaging.



> "The Pentium Pro (up to 512k cache) is packaged in a ceramic multi-chip module (MCM). The MCM contains two underside cavities in which the microprocessor die and its companion cache die reside. The dies are bonded to a heat slug, whose exposed top helps enables the heat from the dies to be transferred more directly to cooling apparatus such as a heat sink. The dies are connected to the package using conventional wire bonding. The cavities are capped with a ceramic plate.
> 
> The Pentium Pro with 1 MiB of cache uses a plastic MCM. Instead of two cavities, there is only one, in which the three dies reside, bonded to the package instead of a heat slug. The cavities are filled in with epoxy.
> 
> The MCM has 387 pins, of which approximately half are arranged in a pin grid array (PGA) and half in an interstitial pin grid array (IPGA). The packaging was designed for Socket 8."



What is your logic for making that assumption?


----------



## Alentia (Mar 8, 2013)

GSP

The assumption I am making based on the following:

1. Pattern, where 512K Cache PPro has double amount of gold vs. 256K Cache. The data is empirical based on my experience processing 256K and 512K Cache chips separately.
2. Urban legend of PPro having 1gr of Gold came from somewhere. There is no smoke without fire. I have spent about 10 years running 2 computer companies until 2000. We had installed many of PPros, but only few with 1Mb Cache. While 512K Cache being most popular, 1Mb Cache were somewhat rare due to price/performance ratio. Back than if I remember correctly prices were around $900 for 1Mb Cache chip, $500 for 512 and about $350 for 256K.
3. Being familiar with computer technologies, back than, trying to beat AMD and Cyrix in the game of speed, all Intel have done to get to 1Mb Cache is to combine 4x256K Cache into the same size die. Time was of the essence, therefore not much thinking was performed by Intel lab engineers.
4. 1Mb Cache chips generate lot more heat vs 512 or 256 and therefore more gold is required to dissipate it.

I might very well be wrong on 1Mb Cache assumption. If I get 1Mb Cache in my hands I should be able to confirm or deny my assumption.


----------



## goldsilverpro (Mar 8, 2013)

Although gold is an excellent heat conductor, the mass of gold on these parts would be so small that it's ability to contribute to the dissipation of heat would be miniscule. One square inch of 60 millionths gold would only weigh about .02g. The purposes of the gold plating is to prevent corrosion of the underlying metals and for good electrical conductivity - that's about it. 

In other words, I can't see how heat dissipation by the gold would even remotely enter the picture. The gold plating thickness on all 3 parts is likely the same. Most every CPU I've seen is plated with 50-60 millionths of 99.99 gold. That's what it takes to prevent discoloration at die attach temperatures (700F for Au/Si braze). No manufacturer is going to use more gold than is absolutely needed. 

From the photos I've seen, the 256K has 2 chips and the 512K has 3 (please correct me if I'm wrong) and these are bonded to to a metal heat sink, most likely with a Au/Si eutectic braze. If so, I can see how the 512K would contain more gold. However, if I understand right, the 1M chips are mounted to plastic and, therefore, this braze could not be used. I would therefore think the gold content of the !M would be less than the other 2, unless there are more internal gold connecting wires in the 1M. I would bet the plating thickness on the legs of all 3 are the same.

I once owned a plating company that gold plated about 50,000 side-braze CPU packages per week for Intel. I realize that those packages are much different than those used on the Pentium Pros, but I do have a pretty good idea of where and how much gold is needed to do certain jobs.

When you are able to process some of the 1M's, please post the results. I, for one, am interested


----------



## philddreamer (Mar 8, 2013)

I found a pic of what looks like a 1 mb fiber PPro. Ther seems to be some gold wires connecting the pins to the 3 chips. Could that be the source of the extra gold. The ceramics, I understand, don't have these wires.
Phil


----------

