Re: AlphaServer 4100 CPU speed upgrade and/or backplane speed ranges

From: Duncan Brown (brown_du_at_eisner.decus.org)
Date: 08/20/05 

Date: Sat, 20 Aug 2005 06:09:22 -0500

Dave Froble wrote:

> Like you said, if you're going to run a system, might as well make it a
> good one. :-)
>
> This is a wild ass guess. I'm not up to speed on some of the larger
> systems. Would the power supplies be an issue? Might the 533 MHz
> boards need more/different power than the 400 MHz boards?

Speaking of making it a good one - I have all 3 power supplies
installed! If it needs different power supplies, I haven't found a
reference to that. It's just that I see processor upgrades mentioned
between the two speeds of any given "flavor" of 4100 system, but not
between flavors, which has me wondering if there is some obscure
difference, like a set of backplane termination circuits that is tuned
to the expected processor speeds, or something.

I installed DECevent and perused the error log a bit. (Wow, that sure
goes into scary amounts of detail, compared to the last VMS version
where I studied an error log... I think if I had parked illegally in the
last day, there would have been a line mentioning it in the error log!)

The time it crashed after about an hour, it looks like it did so because
of an "Invalid Time Queue Entry Format" whatever that means. The crash
after over a day of uptime left no such clue. There were no entries in
the error log from processor boards in trouble, or anything. Just a
bunch of timestamps and then the reboots.

Note that I can't rule out bad hardware. This stuff came from ebay,
after all... But I thought a multiprocessor machine was supposed to
flag and disable bad boards, not just mysteriously crash. And when I
started googling on the subject, I could find *nothing* that talked
about upgrading from a 400MHz board to a 533MHz board in the same
machine...and an old post of Hoff's that talked about backplane speed
differences between the 5/300 and the 5/400... so I began to think maybe
I had done something disallowed, in swapping in the faster boards.

Duncan