I am using a Mac mini, 2012 model, without a UPS. My assumption is that Apple has designed a special adapter to rectify high voltage and low voltage. Is that right? If I use my Mac mini without a UPS and the power surges or is lost, will the hardware be affected by the high or low voltage? Should I use a UPS?
The power supply of the Mac mini supports a range of voltages (100-240V AC), but surges or brown outs may still affect it.
As with any computer, if your local electricity supply is reliable, you don't need a UPS. If your local electricity supply is unreliable, you will benefit from installing a UPS. In this respect the Mac mini is no different from any other desktop computer.