iMac 27" Late 2012 slow down with 24GB

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Bit Baby

iMac 27" Late 2012 slow down with 24GB

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.

1 Reply
JEDEC Jedi

Re: iMac 27" Late 2012 slow down with 24GB

Which slots did the original memory use before the upgrade?

 

I checked the Service Guide and did not see any mention of requiring or recommending a certain order for the RAM.

 

It sounds like you may have a bad stick of RAM or a bad slot since you got beeps when mixing the order of the memory.  How many beeps were there?

 

Test to see if you have a bad stick of memory by removing all the memory and trying one stick at a time in the same slot to see if it boots without any errors.   You can also try running the Apple Diagnostic each time as well or even trying Memtest86 (use Etcher to "burn" the image/iso to the USB drive).   If each stick of memory works fine by itself,  then try a new stick by itself in each of the other slots to see if all the slots are Ok.   If still no issues, try installing just the two new sticks together in the slots your original memory used from the factory.    If you get errors using Memtest86, try running it with your original RAM in the same slots just to make sure Memtest86 is compatible with your system.

 

You may want to blow some compressed air in the memory slots in case some dust has built up in them.  Also make sure the memory is firmly seated in the slots.

 

I'm not sure Crucial is still doing this, but they used to put "For Mac" on the labels of the memory modules when you ordered a part specific for Apple.   Maybe a Crucial rep can confirm the kit part number you posted is indeed compatible with Apple.