DIAGNOSIS That's electronic coil whine, not a sign it's going to fail. It's a common, annoying phenomenon where components (like inductors or capacitors) vibrate at a high frequency under electrical load.
FIX First, identify when it happens. Is it only on a bright white screen? Or when the refresh rate is set to a specific number? Try changing the Picture Mode or lowering the Brightness setting a bit. Sometimes the noise changes or disappears with different power draw levels. Also, make sure the monitor is on a stable surface and the vents aren't blocked, as heat can sometimes make it worse.
IF THAT DIDN'T WORK The whine can sometimes be related to the specific video signal. Try a different input port (switch from HDMI 1 to HDMI 2 or DisplayPort) or, if you're using a high refresh rate, try setting it to 59Hz or 60Hz instead of a variable rate.
HEADS UP Coil whine, while irritating, is generally not considered a defect by manufacturers unless it's extremely loud. If it's unbearable out of the box, your best recourse is to exchange it with the retailer, as LG warranty service may not treat it as a failure.