My iMac is of 2009 and it has 8GB RAM I installed El Capitan 6 months ago in a WD myPassport external disk and it crashed a few days ago. Luckliy, I left the internal HD untouched and had also a backup. I wonder if El Capitan was not suitable to my Mac or was it the fault of the WD external drive from which I was booting and running my Mac? I would like to update to something that is less aggressive to the iMac maybe. Which would be it? I'm really bored with 10.8 but on the other hand, the machine works so well that I wouldn't change it for a newer one. It has worked flawlessly until now with teh El Capitan incident; my fault or Western Digital's The WD was partitioned in 3 sections. #1 =a backup of the internal HD, #2= ElCapitan boot, and the #3 was a backup of all my photos. Each of them was a 1TB partition Following the specs. Hope this helps.