Can I install 2 4 GB SO-DIMM and 2 2 GB SO-DIMM for 12 GB total iMac 27" mid 2011 memory or do all 4 SO-DIMM be the same capacity?
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You won't have any problem if you put memory modules of different sizes. Moreover, you will keep Dual Channel, as you will have two modules of 4 GB and two modules of 2 GB, so this configuration is valid and you can use it if you wish.
The Mid 2011 iMac supports 16 GB of memory officially, but it can support 32 GB. You can buy more memory at OWC or Crucial
Does the order matter? I had 2 2GB simms and added 2 4GB simms in the open slots and got beeping when i powered up. I removed the 2 and put in the 4 and it registers 8 GB of memory.
In that case, it looks like something is not working in the two slots left, indicating a hardware problem. Personally, I would take the iMac to an Apple Store or resellers
Do you have them matching horizontally? 2 x 2 GB next to one another and 2 x 4 GB next to one another? That is how they should be matched up in a mid 2011. I've been running my iMac with that configuration for some time.
Test each module to see if there is faulty RAM or it is not seated properly.
Also, did you purchase the exact spec RAM?
Where did you buy it and what brand is it?
I'll do that. Thanks.
The 4 gb memory modules I purchased online from Mac mall with configuration specified on the Apple support website for my iMac. They work by themselves without the 2 Gb modules that came with the the iMac. I initially put the new memory side by side in the 2 open slots. I'll give another try. Maybe I didn't get them in correctly. Tanks.
Well. I must not have seated memory the first time or the order of the memory matter. My first try the 2 gig memory was in the top slot in the 4 gigs in the bottom slot and now the 4 gig is in the top slot and the 2 gig in the bottom slot. In either case it's now working. Thanks.
Great to hear it's now working! Macs are finicky about their RAM - personally, I only buy from OWC or Crucial.
Can I install 2 8GB in two slots for iMac 2010 Late model?
Read Apple's instructions here:
http://support.apple.com/kb/HT1423#4
Officially, Apple supports up to 4 GB modules in each slot.
Can I install 2 4 GB SO-DIMM and 2 2 GB SO-DIMM for 12 GB total iMac 27" mid 2011 memory or do all 4 SO-DIMM be the same capacity?
