It ended up being a bad motherboard. Turns out the system was still under warranty, so Dell came and replaced it.
Have a poweredge R640 that has been running for 6-7 months without issue. After this past weekend, I came into the office and saw that most of our VMs were unresponsive and attempted to log into iDrac (no success). I restarted the server and iDrac came back up, but showed memory errors in B1 slot. Logs show that the memory was self-healed, but after not being able to boot (stuck at "initializing firmware interfaces") I decided to try a minimal post. There are no pcie cards installed, but removed all hardware except for cpu 1 and memory. Booted a bit further to "enumerating boot options". I've been able to apply the bios update from 2.10.0 > 2.10.2 and 2.10.2 > 2.11.2. That said iDrac doesn't recognize the change, only the dell splash screen shows the bios correctly. Any ideas?
R640 Stuck at Enumerating boot options