Asus Z7S WS - Manual (Page 44)

2-22 Chapter 2: Hardware information
Universal PCIe x16_3 slot (white, @ x8)
PCI_1 slot
PCIe 2.0 x16_2 slot (red, @ x16)
PCIX_1 slot
PCIe 2.0 x16_1 slot (red, @ x16)
PCIe x1_1 MIO slot
2.5.7 PCI/PCI-X slots
The PCI/PCI-X slots support cards such as a LAN card, SCSI card, USB card, and
other cards that comply with PCI 2.3 and PCI-X 1.0 specifications. Refer to the
figure below for the location of the slots.
This motherboard supports the ASUS SASsaby cards (optional) for SAS Hard
disk drive support. For SASsaby M, install the card to the two PCIe 2.0 x16 slots
(red) or the universal PCIe x16 slot (white). For SASsaby 1064E, install the card
to the universal PCIe x16 slot (white) only.