High pitch whine from LCD

I have 3.2" "TFT_320QVT_9341" with touch connected to a Mega 2560 through a "TFT LCD Mega Shield V2.2". It been working great with the UTFT library for the past few months but it it was getting a little slow updating the screen as my project increases in complexity. So I picked up a Due. When the shield and LCD are connected to the Due it runs the program without issue (and much faster!), but there is a high pitched whining noise coming from the LCD (at least the whining is not heard without the LCD attached to the shield). There is nothing else connected to the DUE other than the shield and LCD when this noise occurs, other than the USB cable. Also the pitch of the noise changes slightly depending what it being drawn on the screen. The noise is also present with the Due running the UTFT demos.

UTFT is using the same pins for both the Mega and the Due:
// Set the pins to the correct ones for your development shield
// ------------------------------------------------------------
// Standard Arduino Mega/Due shield : ,38,39,40,41
// CTE TFT LCD/SD Shield for Arduino Due : ,25,26,27,28
// Teensy 3.x TFT Test Board : ,23,22, 3, 4
// ElecHouse TFT LCD/SD Shield for Arduino Due : ,22,23,31,33
// Remember to change the model parameter to suit your display module!
UTFT myGLCD(ILI9341_16,38,39,40,41);

Is it a power issue (the mega being 5V and the Due being 3.3V)? The noise is a bit annoying but I'm more concerned that something will get damaged.

Edit: Probed the pins and get 5V on VCC pin (2) and 3.0V on LED_A pin (18) with the lcd operating on both the Mega and the Due, and the digital pins never see more than 3.3V.

i know i'm necroing here, but did you ever find out why?

having the exact same issue with the same LCD..

No, never did find a solution, and haven't run the LCD on the DUE for very long. I do have a "CTE TFT LCD / SD card shield for Arduino DUE" and a 3.5" TFT LCD on the way so I'm curious to see if this makes any difference to the noise. Will post back when get chance to test them.