An electrical connector system includes a header and an electrical connector assembly. The header includes a leading end having a plurality of contact pins that are insertable into an electronic device and a plurality of separated stripline ground plates extending from the leading end toward a mating end of the header. The electrical connector assembly is coupleable with the mating end of the header and includes a plurality of electrical connectors secured in a stacked configuration. Each electrical connector includes a planar insulative connector body and a plurality of electrical cable terminations for mating with a corresponding plurality of contact pins of the header. At least two electrical cable terminations make electrical contact with a common stripline ground plate when the header and the electrical connector assembly are in a mated configuration.