Thanks. Sorry about that.
The interfaces for mass storage available are three SATA interfaces and one eSATA port available. There is no mSATA port on the motherboard.
Hardware reference for your PC.
/http://www.hp.com/ctg/Manual/c01549447.pdf
Storage upgarde possibilities according to Crucial Memory
http://www.crucial.com/usa/en/compatible-upgrade-for/HP---Compaq/dc7900-small-form-factor