The upgrade was disappointing to some Mac mini fans as Apple stopped offering a build-to-order quad-core processor upgrade and dual-drive storage options that exceed 1TB



From MacRumors:

Many have speculated that the Mac mini also includes soldered RAM, which has now been confirmed by Macminicolo's Brian Stucki. According to Stucki, the RAM in the Mac mini is "not user accessible," which means those who purchase Mac minis are limited to 16GB of RAM that must be upgraded when purchasing the machine from Apple. All three Mac mini models can be upgraded to a maximum of 16GB of RAM, with the upgrade priced at 300 for the base model and 200 for the mid and high-end models. While the RAM is not upgradeable, Stucki says that it is possible to replace or upgrade the hard drive, but doing so may void the warranty.

  New 2014 Mac Mini Has Soldered RAM, Not User Replaceable