First Looks: ASUS P8Z68-V PRO (Intel Z68 Express)
Apart from the USB 3.0 front panel header, there are another three sets of (blue) headers for six USB 2.0 ports and two (black) ones for two Firewire ports.
Just right behind the row of headers, there are three chips. The ASMedia ASM1083 (partially hidden) is a PCI Express x1 to 32-bit PCI bridge, Firewire is provided by VIA's VT6308P 2-port IEEE 1394 host controller and the last one is a Nuvoton NCT6776F LPC Super I/O IC.
A total of seven expansion slots here: three PCI Express x16 slots, two PCI Express x1 slots and two PCI slots.
Only the first PCI Express x16 slot in dark blue is capable of the full x16 link.; the grey colored one can provide only an x8 link while the black one a maximum of x4.
However, as PCI Express bandwidth from the Z68 Express chipset is limited, the default setting in the BIOS is an x1 configuration for the black slot. (First two PCI Express x16 slots are connected directly to the processor.) Alternatively, the user can force 'x4 mode' on the black slot but that will result in the USB 3.0 front header, eSATA ports and both PCI Express x1 slots to be disabled.