R330 alternating fatal errors when installing OS

Recently went to install an OS (FreeBSD) on my R330, and would often get 

"A fatal error was detected on a component at bus 7 device 0 function 0" or the same for bus 5.

Curiously, it would consistently alternate between the two for every boot. I haven't been able to figure out what device is actually on those buses, so any pointers there would be appreciated as well. I've tried a trio of HDDs in RAID 5 and a pair of SSDs in RAID 1.