I am trying to run it at 1066 and not the full 1600. This does not make a difference.
Ok, but if the board is not advertised to support DDR3-1600 modules in general, is it necessarily expected to support DDR3-1600 modules running at 1066? (I don't know whether DDR3-1600 memory is required, or advertised, to be backward compatible with DDR3-1066, although it does often seem to work that way.)
It's tricky to say what (if not incompatible memory) distinguishes your system from others that work properly. It could, as you suggest, be a problem with the FB BIOS, but not necessarily, since many of us use FB successfully. Possibly there is an interaction between different (but correct) BIOS versions and some other problem.
One other thing to maybe consider is the Noctua NH-9UB cooler - some other forum postings suggested reverting to the stock Intel cooler fixed similar problems. This did not make sense to me so I have not yet tried that.
Have you looked at your core temps while the system is under load?