Well... I don´t know exactly what pin 31 does, if anything, but I can tell you for sure that cutting the pin of the motherboard won´t make a difference, and I don´t really see why you should consider that at all... If there´s no pin on the drive, then the pin isn´t connected on the motherboard, so to speak... The wire is physically present in the flat ide cable, but it doesn´t go anywhere...