New 27" i7 - thought I'd have 4 RAM slots but only got 2..

Question

Hi people,
Purchased the 27" i7 with the standard 2x2GB default and purchased another 2x2GB from Crucial at the same time to expand it to 8GB. It's arrived, popped open the expansion slot to get to the RAM at the bottom of the display to find that the 3rd and 4th slots are unavailable, covered over with plastic...
Is this correct that they disable the other unused ports? Or before I break something trying to remove the plastic covers, they are actually removable?
I've not been able to find any mention of this anywhere that having it at the default config it won't be expandable, or otherwise spending a fortune on 2x4GB sticks..

Answer 1

MaximusUK wrote:
Now originally I thought I'd go for a 2X2gb + 4gb config (as not to waste 2X2 gb when I upgrade) but I'm not sure if this would work (does it?). So the other option is to splash out a bit and go for the 12gb with 2X2gb and 2X4gb.
However I have no idea as to the intricate terminology of RAM so could do with a hand in choosing which to buy. For example what does 'ECC' vs 'non-ECC' mean, and soDIMM vs DIMM?
You can do your 2x2GB plus one 4GB stick if you wish on the i5 or i7. These new processors have the memory controller on the CPU die for maximum efficiency. The 2x2GB memory will be accessed via dual channel and run at their rated speed. The lone 4GB stick will only be accessed via single channel and will run slower, but still likely acceptable. Older processors faced with this configuration would run all memory as single channel so the Core i5 and i7 are a welcome improvement. If you go 2x2GB plus 2x4GB from the start, you'll have a total of 12 GB memory all running dual channel at maximum access speeds. Likely would be all the memory you will need, but if you eventually want to go to 16 GB, should be easy to resell the original 2x2GB sticks. If you do not buy your memory from Apple, you may need to hang onto those original 2x2GB sticks and insert them if your computer exhibits any problem that Apple may claim is due to third-party vendors' memory. Or even keep them for your own peace of mind so you can swap them back in whenever something isn't working correctly just to be sure.
ECC - error correcting code - there are extra bits with each byte (eight bits) of data to detect and usually correct any memory parity errors; this would be used by the Mac Pro but is not supported on the iMacs. The first vendor's web site indicates this is ECC memory and it will not work in the iMac.
Non-ECC - no parity error correction; this is what the iMacs support. The second vendor's web site indicates this is the correct memory for you new iMac.
DIMM - dual in-line memory module; just the arrangement of memory circuits in a certain form factor typically used by large desktop computers.
SoDIMM - a smaller form factor DIMM used in laptops and iMacs.