Copper Interconnects continue to evolve as cost effective transmission media options for multiple gigabit networking applications and device-to-device connections. Considerations for the design tradeoffs between added transceiver complexity and tighter transmission media specifications have led to the need to further investigate differential transmission asymmetries and signal pair balance. The paper will investigate deviations from the expected differential insertion loss to pair balance and skew characteristics of the copper interconnect as well as transmitter effects resulting in common mode noise converting to differential noise at the receiver. The paper will utilize the IEEE 802.3ck physical layer (PHY) specifications for 100 Gb/s per electrical lane signaling as a reference model to consider the system level impact of common to differential mode conversion and skew. Simulation models based on transmitter specifications such as signal-to-noise transmit (SNRTX), channel operating margin (COM), and s-parameter models and measurements of cable assemblies, backplanes, test fixtures, and channels will be presented to assess system impact.