Patent ID: 7992019

Claim:
A system device comprising a NIC including a network I/F, a protocol process functional portion, and an encryption process functional portion as well as a controller responsible for overall control, the controller performing, depending on a link status, power-saving control that selectively reduces or terminates processing abilities of the protocol process functional portion and/or the encryption process functional portion by executing for the protocol process functional portion and/or the encryption process functional portion of the NIC a combination of different energy-saving processes corresponding to the processing functions thereof to stepwise reduce electric power consumed by constituent elements of the process functional portions depending on the link status, wherein in one of the energy-saving processes, it is determined whether a protocol process is performed by the NIC or the controller in accordance with the link status, and wherein if the process is performed by the controller, the power supply to the protocol process functional portion and the encryption process functional portion is terminated in the NIC, in another one of the energy-saving processes, depending on the link status, an operation clock frequency is changed in a CPU, which is one of constituent elements of the protocol process functional portion and the encryption process functional portion, and in yet another one of the energy-saving processes, encryption by hardware and encryption by software are switched in an encryption process executed by the encryption process functional portion depending on the link status.