Dell optiplex 790 mini-tower Owner's Manual page 89

Cards
PCI
Mini-Tower
Desktop
Small Form Factor
Ultra Small Form Factor
PCI Express x16 (with support for PCI-Express x1)
Mini-Tower
Desktop
Small Form Factor
Ultra Small Form Factor
Mini PCI Express
Mini-Tower
Desktop
Small Form Factor
Ultra Small Form Factor
Drives
Externally Accessible:
5.25–inch drive bays
Mini-Tower
Desktop
Small Form Factor
Ultra Small Form Factor
Internally Accessible:
3.5–inch SATA drive bays
Mini-Tower
Desktop
up to one full-height card
up to one low-profile card
none
none
up to one full-height cards
up to one low-profile cards
up to one low-profile cards
none
none
none
none
up to one half-height card
two
one
one slim line bay
one slim line bay
two
one
89