For reliable and accurate system modelling of OIF CEI-112G XSR and VSR links accurate channel representation is paramount. Channels are usually measured or simulated in the frequency domain with certain resolution frequency, fres, and up to a maximum frequency, fmax. As baud rates continually increase, fres and fmax are generally limited by measurement instrumentation and/or computational resources. From a practical point of view, a channel is assembled via the cascade of different components (traces, packages, connectors, etc) that may be characterized using different fres and fmax values. In this paper, we investigate the effect of such limitations on the overall system characterization. It is shown via theory and numerical analysis of a typical 112G XSR channel how fmax and fr can severely result in unreliable, sometimes unobvious, channel simulation results. We provide rules of thumbs and possible remedies. An important aim of this work is to highlight that the impact of the limitations is of a fundamental nature and may add significant artifacts that influence the decisions of the signal integrity engineer.