Monitors buzzing when the backlight is reduced is a very common problem amoung LCD monitors. Many models do this and manufacturers deny it every time and will even send it back saying there's nothing wrong with it. Basically if you want to reduce your screen's brightness, reduce brightness; not the backlight of the monitor and it will get much dimmer so you can read easy without blinding your poor little eyes.

Reducing the brightness does not do this, just the backlight; also do not reduce brightness via your graphics software like nividia color controls, do it via your monitor's controls via the built-in buttons on it. For some reason nividia's color controls do not seem to work nearly as effectlively and can actually cause the text to not read well at lower brightnesses, while the monitor's function seems to deliver much lower brightnesses with crisper, easier to read text.

I know this post is rather old, but I wanted to help others experiancing this issue. I keep mine on full brightness for movies and games, and for work/research I keep it at 10%.

The fact that it is common doesnt mean it is an acceptable behavior. IT IS a problem and the vendor MUST repair it (as long as it is in warranty) .

In my case the buzz was coming from a brand-new SONY BRAVIA (April 2010), and on nights it was quite annoying. Playing with the brightness helped, but not enough. And, after all, I was asking myself why I had to watch my new 600$ tv in dark colors?

I asked to all my friends if they experienced a similar behavior with other LCDs. None.

And, in fact there was a problem with an inverter, which has been changed, together with the entire tvboard, in few days by a sony center.

My TV is silent like a sleeping baby now. Again. LCD MUST BE silent.