I'm using the original Arduino with a good voltage regulator, and a RAMPS 1.6 (not the 1.6+) with the adapter card. There are two 10 wire connectors going to the LCD controller. One is for power, and the other is for data. I could use the Reprap monochrome full size graphics controller regardless if the computer's USB cable is connected or not, and it is capable of running the printer. The TFT E3 V3.0 flickers when it gets power from the printer unless the printer & desktop computer with a USB are on simultaneously. This controller says that there's no connection to the printer so it's not recognizing the Marlin firmware for the Reprap full size graphics display. The controller also has an option to run in monochrome mode to emulate a 12864, but in that mode the screen is blank just like a 12864 would be if a 12864 wouldn't be set to run in Marlin.