Thanks, yeah got it sorted now. The silverstone firmware update is confusing as hell - the file names for the firmware don't match the actual version.  Takes a lot of googling to work out which is newest etc....   I found the file on https://www.silverstonetek.com/en/product/info/expansion-cards/ECS06/ - for anyone else wanting to try this it's helpfully called "Fix compatibility issue and support Intel 600 series chipset motherboard"    I shutdown unraid, moved my card