[Beowulf] "dual" Quad solution from Tyan

[Mark Hahn]

> >> http://www.cybernex.co.uk/tyan_vx50_quad_opteron_servers.htm
> > afaikt, this is a ladder design: 
> > 
> > c-c-c-c
> > | | | |
> > c-c-c-c
> 
> Not quite, this would make no use of two HT channels.  Its like this:
> 
> c--c--c--c
> |  |   \/|
> |  |   /\|
> c--c--c--c
> 
> (The two leftmost CPUs need their third HT to connect the two chipsets.)

are you sure about that (ie, inspected the traces, or the HT routing 
tables)?  by your logic, for instance, a plain 4x would have one 
cross-link (and I don't think they do.)