RAID configuration data is written to NVRAM on the controller, but there's also information on the disks themselves that can help you recover the proper configuration.
Page 27 and 28 of this manual seems to suggest the the H800 controller should automatically detect the configuration data on your drives and offer to import that configuration for you. This isn't happening?
As a last resort -- and this will only work if you remember exactly how your RAID was configured -- you can manually recreate the configuration on the new card, but choose NOT to initialize/format the disks. I've had to do this a couple times and things worked out well.
