Model A1174 with 2 GHz Core Duo or Model A1207 with 2.16 or 2.33 GHz Core 2 Duo

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Powers on then shuts off


I have iMac early 2006 20 inch computer.

I've upgraded cpu Intel Core Duo 2.0 ghz -> Intel Core 2 Duo T5600 1.83ghz.

Now computer powers on (power led goes on) but few seconds later iMac shutdowns. (No startup chime etc.)

What is problem?

I've tested with original cpu but same problem.


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Chosen Solution

Examine the capacitors (cans) for corrosion, swelling and or leakage. What are the LEDs in the center showing on boot up? Use the reset and restart gray buttons on the logic board to the left of the LEDs to attempt restart.

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This is early 2006 model (no diagnostic leds) :( And capacitors is ok. Before CPU upgrade iMac worked well.

I've tried many cpus but no success. Only power light goes on and hdd starts (no startup chime) 5 seconds after iMac goes off.


Please give the last four figures of your serial number, (located on the bottom of the stand).



EMC No.: 2105

iMac 20"/2.0GHZ/512MB/250GB/SD/AP/BT


Apple iMac "Core Duo" 2.0 20-Inch Specs

Identifiers: Early 2006 - MA200LL - iMac4,1 - A1174 - 2105


Here's the guide for the CPU upgrade but that does not appear to be your issue. Try disconnecting the hard drive cable and see if it will boot from the original system installation CD.


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