My daughter has a 20" iMac, SN YD91224786, Intel Core 2 Duo, iMac 7.1, 800mhz, with 1 GB of ram. Per recommendation of Crucial I purchased 2each 2gb CT2566AC800.K16F (I think, it's hard to read the numbers). Total of 4 GB ram. When I install both 2gb chips the machine will not start. If I install one 2gb chip and the original 1gb chip the computer will boot with this 3gb setup. I have tried changing slots,...every combination possible but it will not boot with 4th. The machine is supposed to recognize 4th of ram. Each chip works fine in either slot, but two will not work together. What could this be?
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