Patch cords need to meet the TIA/EIA-568-B.2_ standards for data transmission for Ethernet or you run the risk of forfeiting peak transmission performance in you network. The cost of manufactured compliant patch cords is very low but the resulting cost of using non-compliant cords can be very high. Many times I see network personals making patch cords for cat6 cabled networks but never testing the patch cord unless there is a continuity problem (Hard failure).  Performance factors such as cable lengths, NEXT, FEXT and Return Loss should be considered in the performance of a patch cord before using it on a network.