User's Manual

Specifications 81
Power Requirements for Devices You Can Connect
Expansion cards
m Maximum power consumption by the AGP card is 20 watts (W).
m Maximum power consumption by four cards and the AGP card combined is 55 W.
USB devices
m Each of the computer’s built-in USB ports is allotted 500 milliamperes (mA).
FireWire devices
m The computer can provide up to 15 W total to the FireWire ports.
System Clock and Battery
m CMOS custom circuitry with long-life lithium battery. You can replace the computer’s
battery (see “Replacing the Battery” on page 71) with a new one purchased from an
Apple-authorized dealer.