I have a Cobra 030 and you've reminded me that the early Cobra cards would not work with fastram using Kickstart 3.1. Amiga resource.cx gives information on it. IIRC there is a flsh utility to update the Cobra on-board rom to run. Maybe with Kickstart 3.0 there is also an issue because 3.0 doesn't autoconfigure ram but 3.1 does.
http://amiga.resource.cx/exp/cobra
