Save money on iMac memory: OWC memory for iMac.
The new iMac 5K and iMac 4K are available for pre-order at B&H Photo, see late 2015 iMac 5K / 4K buying recommendations. MPG gets credit when ordered through B&H ads/links on this site. AppleCare for iMac is a better deal at B&H than at Apple.
MPG reviewed the 2014 iMac 5K in detail and much of what was found there applies in general to performance, but much has also changed, and it is all very welcome. A maxed-out 2015 iMac 5K will be reviewed here soon.
These are excellent reasons to prefer a 2015 iMac 5K over the 2014 model, though casual users are not likely to care much about most of this.
- The 2014 iMac 5K has a marginal color gamut; according to Apple the 2015 iMac 5K offers a much improved gamut (range of colors/tones). Apple’s support for the new “P3” color space in Apple Photos is laudable and a major leap forward in color gamut for Apple displays, which until now have been terrible for color gamut. [Various ignoramus press write about whether they can see more colors, failing to understand that color gamut is image specific, requires proper image processing from RAW format (camera JPEG originals are at best AdobeRGB and usually sRGB), and that human vision varies greatly in color discrimination].
Note that as a choice for serious photographers, 16-bit ProPhotoRGB remains a far superior choice for “master” images, since today’s digital cameras easily produce images out of gamut for either color space, and printers can render colors out of range of AdobeRGB or P3. See Understanding Wide Gamut Displays as well as My Workhorse Wide Gamut Display: NEC PA302W.
- The 2014 iMac 5K had a reasonably fast SSD (flash) drive; the 2015 iMac 5K has one about 3X as fast and about 1/3 faster than the 2013 Mac Pro.
- The 2014 iMac 5K was limited to 32GB memory; the 2015 iMac 5K can take up to 64GB memory.
- The GPU (graphics) are improved slightly.
Missing from the 2015 iMac 5K is the transition to unified Thunderbolt 3 and USB-C ports. Apple must be holding off on this technology switch until 2016 in order to roll it out across the product line, and perhaps at that time the Mac Pro will get an update.