It looks to me as a hardware error with your motherboard and CPU IMC but at early stages I can no way be sure.
What exactly is the motherboard model?
Tyan 2932G2NR is quite a generic name that I could not track back but the only similar ones we have are Tyan 2932G2NR-E and Tyan S2932WG2NR. Is yours any of these?
Which version of BIOS are you on?
Also, which power supply are you using.... not the Antec TruePower 2.0 TP-550EPS12V I hope.
Try the 64-bit version of FreeBSD. 64-bit will aggravate memory and CPU IMC far more than 32-bit can and if either of them are faulty or problematic, it will error very quickly which will give us some more insight. Most likely it won't even boot in those cases. http://www.freebsd.org/platforms/amd64.html