DIAGNOSIS This is coil whine from the monitor's internal power supply or circuitry. It is a physical phenomenon, not a defect that affects performance. The sound often changes pitch with varying screen brightness or on-screen content.
FIX First, disable any dynamic contrast or power-saving features. Press the joystick. Go to Picture > Energy Saving. Set it to Off. Navigate to Picture > DFC. Set Dynamic Action Sync to Off. These settings modulate power draw and can induce whine. Set a fixed brightness level, ideally between 40-70%.
IF THAT DIDN'T WORK The whine may be exacerbated by the GPU's output signal. Try a different refresh rate. In NVIDIA Control Panel or AMD Adrenalin, create a custom resolution with a 144Hz refresh rate instead of 160Hz. Test. Also, try a different certified DisplayPort 1.4 cable.
HEADS UP Coil whine is often more audible in quiet environments and can be position-dependent. It does not indicate impending failure. If the noise is loud and constant from day one, contact LG support within the warranty period for a potential unit replacement, as whine severity varies.