The ASUS P7H55-M Pro mainboard is a mATX board. It has 2 PCI slots, 1 PCIe x1 and a full length PCIe x16 slot.  Behind the PCIe slots are the audio and GbE controller chip. Near the PCIe x1 is the CLK GEN. To the right, we can see a heatsink on top of the Mosfets. The power connector is right next to it.

At the bottom left of the mainboard, we can see the connectors for External USB brackets, 1 IDE port, 6 SATAII ports, 24 pin power connector and 4 DIMM slots supporting up to 16GB of DDR3-1333 (oc DDR3-2133).

On the back panel are the PS/2 Keyboard 6 USB 2.0 ports, 1 GBE, 1 SPDIF, 1 DVI-D, 1 D-SUB, 8 ch audio ports