Bruce C. Miller <bm3719@gmail.com> wrote:
> I have a E420R with 4x 450Mhz CPUs. In an effort to conserve power and
> air conditioning in my computer room, I decided to yank two of the
> CPUs.

> According to the manual, running a E420R with two CPUs is fine, but you
> have to remove CPUs 0 and 3, which I did, leaving the two middle CPU
> modules. Upon rebooting the server, I get a blank white screen. No logo
> in the upper left. Nothing. I thought maybe there was some kind of
> jumpers or something I might have missed, but there is no mention of
> anything of the sort in the manual. It does recommend putting blank
> placeholders in the empty CPU slots and I don't have any of these,
> however it's hard for me to imagine that they do anything.

> Any thoughts?

> What's worse is that putting the two removed CPUs back and restarting
> results in OpenBoot starting up normally, and then freezing after the
> memory scan. This computer worked fine prior to this!!

Yeah, you disloged the memory or the backplane enough to cause a
problem. Have you checked both of those? I dealt with a lot of 420Rs
and sometimes had problems with this just when people moved them from
rack to rack. The connecting system for that backplane doesn't seem to
be the most reliable design and if I remember right it was also
connected at least partly to the CPU cage as well, you could have
disrupted it just by pulling the CPUs. There are some screws holding
the whole CPU cage down, make sure those are tight, also the two wacky
screws on the memory backplane. You're supposed to use a torque driver
on these according to Sun and there might even be one stashed inside the
machine, but if not careful hand tightening is probably ok.

I don't know why they actually split each bank across that
backplane instead of making two banks on the main board and two on the
back plane. If they had done that, at least you could have ripped out
the backplane or not even used it if you didn't need the extra RAM.