Sony PCV-RX270DS - Manual (Page 40)

VAIO Digital Studio Reference Manual 26
5 If you do not replace the card or install another add-in card, install a
slot cover over the vacant slot at the rear of the chassis (see
“Covering
an Open I/O Slot” on page 36).
6
Replace the side cover (see “Replacing the Side Cover” on page 23).