[geeks] sun ultra 24

[nate at portents.com]

> Huh?
>
> FB and ECC are not in competition.

Yes they are in competition in the server/workstation market, depending on
the platform.  Multi-socket AMD means ECC *non* FB-DIMMs, multi-socket
Intel means ECC FB-DIMMs.

> My Mac has fully buffered ECC memory.

Yes it does, because it is multi-socket Intel.  And FB-DIMMs currently
consume a lot more power than non-FB ECC DDR2.

8GB of non-FB DDR2 memory uses 36.94 watts under full load vs. 101.2 watts
for 8GB of FB-DIMMs.  When idle, non-FB DDR2 memory uses 14.32 watts vs.
83.34 watts for FB-DIMMs.

This adds up quickly in data centers where you have lots of memory
installed in lots of servers.

FB-DIMMs do have some advantages (latency not being one of them, and their
performance issues are largely masked by the massive on-chip L2 caches
that Intel uses as well as a lot of extra work they put into their memory
controllers).  FB-DIMMs can be set up to have failover modules so in a
situation where a module goes bad in use, the motherboard can stop using
it and switch to it's mirrored module (similar to RAID) without missing a
beat.  And there are companies working on new FB-DIMM modules which will
use less power and generate less heat, and should be coming to market in
the not too distant future.

However contrary to what some people have written on this list, I don't
consider 36w vs. 101w a negligible power difference.

- Nate