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Fried Chicken

Original poster
Jun 11, 2011
Or at least I thought I knew.

I plan on buying 16GB of memory for my iMac (arriving Friday :D) so I would have a grand total of 24GB of memory.
Based on this thread, you would want to replace the apple RAM with the new RAM and put the 8GB of apple RAM in the two remaining slots. This way if you got memory with lower CAS latency than apple's CL11, you wouldn't downclock your RAM to 1333 MHz.

So now I've narrowed the choice down to three RAM modules.
First is the one I would trust to be 100% reliably with the iMac:
Crucial's 16GB dual kit - $85, with a CAS latency of 11 (like apple)

Then there's the next choice for about the same price:
G.Skill's 16GB dual kit - $81, CAS latency: 10. Same price, with reports that it'll work in the 2012 iMac but not in other Macs.

Finally there's the big daddy:
Kingston's HyperX 16GB dual kit - $130: CAS Latency: 9.
Some guy has verified that it'll work with the 2012 iMac.

So now the question is, which one do I get? Does CAS latency play a big difference? Should I worry about mixing apple RAM with lower latency RAM? I plan on upgrading to the full 32GB at some point in the future when it'll be like $30, but for now I think 24GB should suffice (haha my current imac has 2GB maxed!)


macrumors member
Jun 10, 2004
You aren't going to know the difference my friend... :)

I've used Crucial for 8+ years on 5 different machines, never had a problem.


macrumors G3
Mar 29, 2008
The Corsair Vengeance 16GB kit is highly reviewed and confirmed to work in the late 2012 iMac as well. I tend to prefer Corsair over most for their customer service and warranty. Crucial would be my second choice after them.

I wouldn't bother with the Kingston. It's wasted in the iMac. Get the Crucial or the Corsair. I have the Corsair, which is CAS 10. I got it because it was cheaper than the Crucial at the time I bought it.

My advice to you: Get whatever's cheapest. There is absolutely zero tangible difference between the CAS 11 Crucial memory and the CAS 10 Corsair, and take that for someone with the Corsair. Someone put up some benchmarks of both the CAS 11 and CAS 10, and it was so close between them that simple variances between the tests might have accounted for the few points of memory speed the Corsair had over the Crucial. The difference between the Corsair and the CAS 9 Kingston is probably a similar story.

Save your money and go with whatever's cheapest. FYI I'm running the Corsair Vegeance, 4x 8GB for 32GB total. Works just fine.
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