Hi, Just updated RAM in my 27" Late-2012 iMac 2.9Ghz Intel Core i5. It had 8 Gb but I have added 2 x 8 Gb of Crucial 1033 DDR3 RAM which I pulled from my 21.5" iMac so now have a total of 24 Gb. Now I recently upgraded to 10.8.3 and now i'm having Graphics issues where scrolling in Chrome or Safari is causing the window to Jitter, also happening when scrolling Applications folder or when i'm opening photos using QuickView. Just wondering if anyone having same issue since updating to 10.8.3 I have tried resetting PRAM, also think I had an update for some Apple Intermedia Codecs today too for Motion 5. Thanks Kevin.