Inspiron 15R high pitch noise

Hello

I recently bought an Dell Inspiron 15R (Inspiron 5537) and I have a weird problem with it. The problem is, that display backlight (or probably its regulation circuit) is making an super annoing high pitched noise that is driving me crazy. Im guessing, it is a backlight because if i turn the screen brightness to full, noise dissapears and notebook is completely silent.

What can i do with it? Should I ask for a warranty ? Or is there some other way?