Between 500mA - 3A at 5 Volts (2.5 - 15 Watts), depending on the brightness setting and number of colors used. (All white at full brightness is 15 Watts, but normal use even on full brightness is typically under 7 Watts.) The power adapter that ships with Game Frame is 8A just for good measure (100V-240V).
Why is power dependent on the number of colors? Because each LED pixel actually contains three tiny LEDs: red, green, and blue. You mix them to create colors, and if all three are turned on equally you get white.