[rescue] what's different between IBM PC Server 325 8639-1RY and 8639-2RY?

[Greg A. Woods]

DAMN!  I've been stimied by IBM.

My colleage, one of my clients, and I had purchased a number of surplus
IBM PC Server 325's, model 8639-1RY, a few years ago and have been more
or less using them happily ever since.

Recently my client wanted to stuff one or two with as much RAM as
possible to handle more load.

These things take 60ns ECC EDO "buffered" (i.e. registered) 168-pin
DIMMs of up to 256MB each, and there are four DIMM slots.

Now here's where it gets interesting.  The -1RY is listed in the
spec. seets as allowing 512MB, but the -2RY is listed has allowing
1024MB.  (IIRC all the older P-Pro models allow 1024MB too)

The spec. sheet is the only place any limit on the memroy size is
mentioned.  No limit is mentioned in the "generic" User's Handbook, nor
in the Hardware Maintenance Manual covering those models.

Indeed both the HMM and the HMM supplement say that all the FRUs are
identical in both models -- i.e. all the circuit board have identical
FRU part numbers.

They also both run the exact same main BIOS code.

The only documented difference between these two models appears to be
that the -2RY was shipped with the remote management board installed,
and with a 333MHz processor instead of a 300MHz one.

When we originally bought the machines I was sure the spec. sheet was lying.

Unfortunately the spec. sheet seems to be correct.  We've been unable to
boot a machine with four 256MB DIMMs installed -- indeed it apparently
hangs after checking the first 512MB.  I'm sure we've tried everything
anyone could possibly suggest to rule out bad parts or installation
problems.  It won't even recognize any smaller DIMMs in addition to a
pair of 256MB units.  We've updated the BIOS to the latest rev. and
still no go.

If anyone happens to have a -2RY model I'd appreciate it if you could
open it up and find the part numbers of the CPU daughter card and the
planar card, as well as numbers on any stickers on any EPROMs or what
have you....

The only things we can think of are either there's some difference in
the 333MHz Slot-1 CPU module, or maybe there's more BIOS code on the
management adapter, or maybe some feature select line on the connector
it uses, or perhaps there's a serial number burned into the motherboard
somewhere and there's a separate range of numbers for each model line
and the BIOS artificially limits the RAM size.

Oddly I can't find any mention in the Hardware Maintenance Manual or its
supplement regarding special procedures for changing any parts on either
model, though perhaps there's some secret service manual that's not
searchable, or even mentioned, online.

I thought all Intel Pentium II processors could easily handle 1GB of
RAM, although only some steppings could properly cache as much as 4GB.
(They all have a 2^36 byte physical memory address space.)  So that
would seem to rule out anything dependent on the processor, leaving only
the management adapter as the unique difference between the models.

(if anyone has a -2RY model they'd like to sell cheap, let me know!)

-- 
								Greg A. Woods

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