Can be options.
Try to start with getting into the Configurator of the controller - I think that for your server you need to press F8.
To be sure - see the manual or find out from those who told about the old discs. What you will see inside, should provide a basis for reflection.
according to there were two AA, they were removed, put two SSD Samsung
Also, are you sure this upgrade is possible without updating the firmware of the controller, or in General?
Under "General" I mean a situation where the options of drives for use restricted to a list of part numbers (often with proprietary firmware).