There are three PCI Express slots: two physical x16 connectors that run x8 mode each, and an x4 slot.
We used three graphics cards here.
Using three graphics cards permits a maximum of six displays.
Intel's Northbridge heat sink is of impressive size and works efficiently.
More SATA: The Si3114CTU by Silicon Image adds four more ports. It supports NCQ and RAID levels 0, 1, 1+0 and 5.