I have a iMac (27-inch, Late 2012) 2.9GHz i5 I have 8GB memory from Apple (2x4GB) and I installed 16GB(2x8GB) crucial (CT2KIT102464BF160B) and from booting to using the computer it is super slow only even typing sometimes there is a huge lag. I have installad on the following configuration from Top to Bottom slot when unit is upright 8GB - Crucial memory 4GB - Apple memory 8GB - Crucial memory 4GB - Apple memory if I swtch positions my computer won't turn on just beeps.
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