This paper describes various embodiments that relate to personal computer systems, and accurate initialization of computer hardware of personal computer systems from a low-power and/or power-off state. According to one embodiment of the invention, a computer system includes a device operative to be powered down to the power-off state dependent upon an amount of user activity on the computer system. The computer system also includes a device controller operative to initialize the device from the power-off state to a power-on state responsive to user activity on the computer system. The device controller has at least one sensor device operative to determining a physical variable related to the device, and operating characteristics of the device are related to the physical variable.