I'm about to buy an iMac. It will be used, and I have a (probably short-lived) shortlist from which to choose from. I'd made up my mind on a 2013 27" i7 3.5 with a 3Tb fusion drive. Then I found a 2015 5k i5 3.3 with a 1Tb fusion drive, according to the serial number. But the screenshots on the ad say it's a i5 3.2. The price difference is actually minimal between the 2013 and the 2015 models - but I think I may be able to deal he 2013 price down. I'm a photographer - so I'm looking for speed. I like the idea of a retina mac, but I'll be using a non-retina macbook in tandem with iMac. Storage space and speed are the primary requirements. Checking the Everymac details, the Geekbench scores are almost all better than the 2015 model, and definitely better than the 3.2Mhz model. So which one? And is the 2015 dodgy because of the serial number vs system report difference...?