Sony PCV-RX791 - Manual (Page 27)

Identifying Components 15
Expansion Slots
There are three expansion slots. Expansion slot No. 1 is occupied by the
fax/modem card. A V.90 compatible modem has two jacks (Line and
Telephone).
Expansion slot No. 2 is occupied by a Giga Pocket™ card.
Expansion slot No. 3 is available for expansion.
There is one AGP slot (No. 4), which is occupied by an AGP card.
See online specifications sheet for details.
Slot No. 4 (AGP)
Slot No. 3 (PCI)
Slot No. 2 (Giga Pocket card)
Slot No. 1 (Fax/modem card)