Part of it is operating at a more efficient point on the VF curve. The other part is that Intel parts increase voltages by ~2.5mV every for every degree C closer to TjMax. A part at 95C@253W has a 50mV worse VF curve than a part at 75C@190W which can be a substantial efficiency difference.
They skipped an interesting range around 190W where you barely lose anything in performance
Part of it is operating at a more efficient point on the VF curve. The other part is that Intel parts increase voltages by ~2.5mV every for every degree C closer to TjMax. A part at 95C@253W has a 50mV worse VF curve than a part at 75C@190W which can be a substantial efficiency difference.