iMac RAM upgrade

Highlighted
Bit Baby

iMac RAM upgrade

Have couple of questions relating to a mid-2011 27" iMac RAM upgrade.

 

I have the original 2x2GB chips, but want to increase my RAM.  Apple states 16GB is the max this machine can utilize; others state it can use 32GB.

 

So first off, although this iMac might operate with 32GB, can it actually utilize all that RAM?  Would I be better to keep the RAM at 16GB or less?

 

Next, I want to keep the 2x2GB chips and add a pair of matched chips.  If I add 8GB (2x4GB), would the CT2K4G3S1339M 2-pack be the same as two CT3373715?

 

Thanks.