Hi guys, I posted this on Reddit but had no luck with getting a good response. So thought you all could help me! So I have a mid 2010 Mac Unibody (the white one), and I recently upgraded the RAM to 8gb (2 x 4gb units). But when I go onto the memory tab on About This Mac, it says that only one of the slots is active. I have definitely bought the right type of RAM and I've installed it correctly (I've taken it out and put it back in several times). Any idea what I need to do to make it work? FYI I'm running Yosemite and have over 100gb of memory free on a 250gb hard drive. I bought this RAM: http://www.ebay.co.uk/itm/361183094170 Any help would be hugely appreciated.