64bit P4 vs mfsBSD

[Quartz]

Not sure if this is the right place to ask mfsBSD questions.

I have an old Pentium 4 server and I'm trying to figure out exactly what 
the cpu is, but I don't want to have to disassemble the whole thing if I 
can avoid it. Intel's cpuid utility, various linuxen, and wikipedia are 
giving me conflicting info about the model and 64bit-ness, so I thought 
I'd see what sysctl had to say and boot mfsBSD.

... except it doesn't work. I tried both 10.0 i386 and 10.1 amd64 and 
both of them hang. 10.1 amd64 gets to the beastie menu, but regardless 
if I select multiboot or single user it gets as far as the white-on-blue 
"Booting..." and then just stops. 10.0 i386 seems to die somewhere in 
stage two before the menu even appears. It's not a case of corrupt 
download or borked build because the same jumpdrive boots my other 
machine just fine.

Any thoughts?