(Sorry for the lack of exact error messages in the following. It's about
a machine that's at the office, and is currently powered off, while I'm
at home.)

We have 2 P6 systems with Adaptec 2940UW controllers and dual Seagate FW
Barracudas that we've been using with 0 problems for about 10 months
now. 

We just took delivery of 4 new Intel Providence motherboards with
builtin 7880 SCSI controllers, and 6 Seagate 34501W "Cheetah" disks (the
new 10,000rpm ultra wides). Once we got everything setup and recognizing
the SCSI disks (3 of them connected to one machine; they're to be
striped), I successfully put disklabels on them, then tried to run
newfs. The first time I run it after boot, it will get a short way
through the operation then stall; after a long pause it prints out an
error (usually a write error). After that, all attempts to do newfs
immediately fail with an error. When I look in /var/log/messages, it
shows timeouts and bus resets by the SCSI controller.

I thought it might have to do with the cabling or termination (these
disks are in external cases), but when I bring the system up into the
SCSI controller's diagnostic ROM, it is able to format and verify the
disks with no problems whatsoever.

This machine is running a 1.2.1 kernel (booted off an IDE). Have any
changes happened in the ahc driver since the revision in 1.2.1 that
could make things work better? If so, is there an incarnation of it that
will compile into 1.2.1?

Any help is appreciated, as these machines are supposed to go into
production by the end of the week. (If anyone would like more details on
the error messages, I'll be able to get them once I get to the office
and turn the machine back on in the morning).