It is definitely the raid card. Removing it lets booting proceed as normal.
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.
R330 alternating fatal errors when installing OS