Often the Diagnostic LED POST Code shown is the last one the system was able to achieve before a failure/error occurs. The LED code you indicate corresponds to a 33h Hex BIOS code. The 3xh codes are Pre-EFI Initialization Module (PEIM)/Recovery conditions. 31h is Crisis recovery has been initiated by software (corrupt flash) and 34h is Loading crisis recovery capsule.
Looks like you might of had a corrupt flash condition that was unable to load the crisis recovery capsule to recover.
the server crashed again. Moved the data to failover system. I have the slight impression, that the external raid-card (3ware) is broken. Last message on the screen after boot was somethin like "...configuring ... 3ware ...." with the same LED combination as mentioned above.
Could a broken controller card cause such an error status?