Best way to insert memory sticks of different GB size on iMac 5k 2015
I have 2x4gb factory memory sticks and just ordered brand new 2x16gb sticks. What is the best way to insert them, so that the 16gb sticks are used first.
RAM needs to be installed in matched pairs. RAM pairs are not used first and second, so your question regarding which is used first is moot. Follow Apple's instructions for installing RAM in Install memory in an iMac - Apple Support