boot failure with twa device

[Dewey Hylton]

anyone up to the task of helping me solve a freebsd boot problem?

hardware:
core2quad, 8gb ram, x16 pcie video, x16 pcie raid (3ware 9650se)
motherboard: Asus P5N-E SLI / bios 1101 (20080707)

amd64 bootcd: hangs when attempting to init raid (timeouts, bus resets)
i386 bootcd: same as amd64 EXCEPT works with APIC disabled.

results seem to be the same on 7.0-RELEASE, 7.0-STABLE-0807, and 8.0-CURRENT
i don't believe it's pcie contention because replacing the video with
pci yields same results and because
this machine runs flawlessly, 64bit with APIC, with linux.

can something possibly done, say hint.twa.0.xyz='foobar', to init the
raid card as linux does? where do i start?
bios for both raid and motherboard are up-to-date, but the symptoms
were the same before and after updating both.

thanks in advance; this one has me stumped and i haven't had luck with
the lurkers in irc either.