Whats New and Different

1. Important: The logic board has 3 thermal pads on the bottom side of the logic board. These pads must be changed each time the main logic board is removed from the bottom housing. Failure to replace these pads may cause the microprocessors to overheat and become damaged. (An exception would be if you are simply testing the logic board and only detach it for a few minutes.)

Refer to the Take Apart chapter, "Thermal Pad Installation".

2. Important: The CPU uses a thermal pipe to transfer heat away. This pipe has a thermal connection to the top metal chassis (Faraday cage). This connecting point must be cleaned and have new thermal paste applied to it each time the bottom housing is removed. If the mating surfaces are not cleaned and thermal paste is not used, the CPU may overheat and become damaged. There is no exception to this. Note: Most service procedures require the bottom housing to be removed.

Refer to the Take Apart chapter, "Thermal Paste Application".

  1. Important: The bottom plate has 4 screws that must be tightened to at least 17 in.-lbs. If you do not have a torque driver, you will have to make sure these bolts are firmly tightened (by hand or purchase the service tool (076-0899) in order to ensure the thermal pipe is firmly mated with the top base. If the bottom plate is not securely attached to the base in this fashion the CPU may overheat and become damaged.
  2. Special service tools are required to perform some procedures. A service stand, 076-0898, to hold the unit during take apart and service cables, 076-0897, that allow the unit to run while the bottom housing is open. Important: Diagnostic service cables allow the unit to run while the bottom housing is open; however, the computer cannot run for more than five minutes with the bottom housing open. If it is open longer, the CPU may overheat and become damaged.
  3. The CPU is now G4 based, running at speeds of 700 MHz and 800 MHz.
  1. The display is a TFT LCD panel with a maximum resolution of 1024 x 768. The display is connected to the unit via a tilt and swivel neck extension.
  2. Optical drive is now tray-loading, and is either a CD-RW, a DVD-ROM/CD-RW (Combo drive), or a DVD-R/CD-RW (Superdrive).
  3. The computer contains a variable-speed fan. The fan speed increases as the unit needs more cooling.
  4. The unit does not have NMI or Reset buttons. These functions have been taken over by the power button.
  5. The sound-out port supports external digital audio speakers.
  6. There are three USB ports on the iMac (Flat Panel); previous iMac models had two USB ports.
  7. The iMac (Flat Panel) houses a different A/C power cord; power cords from older iMac models will not fit into the A/C socket.

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