The ECS PN2 SLI2 Extreme motherboard allows two expansion spaces between the first and second PCI Express x16 slot. This arrangement is more accommodating for larger dual-slot videocard heatsinks. The two PCI Express x1 slots surround the first orange PCI Express x16 slot, while the PCI Express x4 slot is located just above the second blue PCI Express x16 slot. If you run two videocards in SLI, both at 16 lanes each, connect up the auxiliary power connector at the bottom corner by the battery.

The PN1 SLI2 Extreme has a parallel printer port on a bracket. If not needed, there is no reason to connect this to the header shown here. Most printers are USB these days, but legacy devices live on.

In this corner we have the official nVidia MCP55 chipset heatsink, six SATA connectors (with RAID support) the front panel header connector and some USB headers. The floppy drive connector is tucked in, out of the way of other devices.