The PowerPC ECI Card is required to use the Expansion Chassis with a PowerMac. The Classic ECI will not work.PPC ECI Card goes in the computer's Slot C (center slot)Chassis Slot ID switch settings: 0 1 2 3 4 5 6 7 8 9 A FDuplicate slots: NoneTotal number of slots available: 14Card Order (L-R facing front): Disk I/O, Bridge I/O, DSP Farm, SCII* Non-Digidesign cards (video cards, etc) cannot be placed in the Expansion Chassis. They must go in the computer.** Expansion Chassis under serial number #220 must have modified motherboards in order to work with the PPC ECI card.The Power Mac version of the ECI does not require the use of Expansion View or DigiTest to configure itself for use in the various supported CPUs (the Upgrade Chassis ROM menu item will be greyed out). It also does not display the "expansion chassis" icon when the Mac is booting.