I have a 27" iMac and recently picked up the latest model MacBook. I also picked up a 4Gb (2x2) RAM. I placed the 4Gb in the MacBook and decided to place that 2GB from the MB in my iMac to boost it to 6GB. Here is my question, did I place the RAM in the best slots, assuming there is such a thing as best slots. I remember from the old day of PC that there was a strict order for placement else I may not get the most out of the additional RAM. It does register as 6GB when I click on 'About This Mac'. Below is a diagram and screen shot to show exactly what I did.