I've updated to the latest 1.49FW, unfortunately it shows the same error as as the previous controller which was returned to the dealer.

On boot-up it sometimes fails drives randomly (red flashing light next to drive) when detecting the drives and array. It requires a complete cold shutdown to reset the drive error. There is nothing wrong with the drives as far as i can see. Sometimes it also hangs indefinitely when detecting the controller card with the message 'please wait for the F/W to be ready...'.

Seems to point more and more to an incompatibility between the Areca 1880 drive and the 836-E1 SAS enclosure with LSI expander.

To be continued..