Alienware X51 R2 Motherboard Diagram: //free\\

Back Panel Ports. Network adapter One RJ45 connector. USB Two USB 2.0 ports. Four USB 3.0 ports. Alienware X51 R2 Specifications - Dell

The rear of the motherboard provides a dense array of connectivity: Alienware X51 Service Manual - Dell alienware x51 r2 motherboard diagram