2 1tb hdd fitted not initializing now show 7.3tb and won't format

Help having some trouble. Recently put new ram riser board in and mac pro seems to be fine running osX 10.5 leopard occasionally won't turn off so have to hold down power button. But I thought what the $&@# get two new HDD's and upgrade the system and a fresh install. Reinstalled osX. Inserted both HDD's accepted them fine formatted to mac OS extended journaled was fine tried another reinstall as wanted the OS on my new HDD's and it came up with both new drives not initialised and disk utility will not allow me to format it just says error on in/out. Used terminal to disk until format and still showing as 7.3tb and not the 1tb that they actually are, and in terminal says error with erase the underlying task reported failure on exit (-9972) any help most appreciated :)