They're different chips - the laptop chips get much better perf/watt than the desktop components which are comparatively sloppy. That power management hardware

They're different chips - the laptop chips get much better perf/watt than the desktop components which are comparatively sloppy. That power management hardware is actually somewhat expensive technologically. It really has more to do with the customers. The people buying these chips by the thousands are Enterprise Desktops, and keeping power bills down is their #1 goal. The customers don't buy GPUs in these machines either, they expect Intel's to be "good enough." Unfortunately, consumer desktop purchases are basically a rounding error to Intel's multibillion dollar balance sheets, so they don't build parts for that segment. Instead, they blow some fuses on their enterprise parts and sell them as "Extreme Performance", "Enthusiast Desktop" or whatever other euphemism they want to use for "overclockable" these days.