Another model reference.
The Sophos SG 115w (rev 2) - Intel E3827 (@ 1.74GHz), 4GB DDR3L, and 64GB SSD (SATA 6Gbps).
Bios adjustments
change boot order so usb stick is first
disable the 60/40 emulation
changed the comm port speed to 115200
Installed the pfSense v2.7 CE memstick build without any complaints.
eth0 = wan
eth1 = lan
eth2 = OPT1
eth3 = OPT2
ath0 = Wireless
Only issue I had with the few units was the cmos battery needed to be re-taped down, otherwise no issues.