We measure power consumption at the socket via a calibrated meter – system wide. As the Dell XPS 18 is an all-in-one PC we include the monitor.
Power results were measured at idle and when loading the system with the Catzilla benchmark.
Leaving the system at idle we measured 19 Watts. The XPS 18 All-In-One is very power efficient and should not have a noticeably negative impact on electricity bills.
My brother has this for work, he works as a manager of a mobile phone retail store. Its very useful for a lot of tasks. But it is quite a bit of effort to carry around. Good screen size though for presentations etc.