I am very touchy when it comes to noises. For me, a monitor has to be absolutely silent – even the slightest noise annoys me immediately. I went through an odyssey with the Samsung SyncMaster 245b because of its noise emissions which ended with me returning the screen to the dealer.
Unfortunately, almost every screen does emit noise of some kind. No power supply is perfectly silent and usually you can hear it when you listen closely to the back of your screen. Worse is usually the noise that is often emitted when monitors are dimmed in brightness. These are often much louder than the power supply and in contrast to the latter much easier to notice in front of the screen.
The power supply of the Dell UltraSharp 2709W is relatively peaceful. As usual you can notice it when you are listening behind the screen, but in front of the monitor I can not perceive it.
As expected, the dimmer is more troublesome. In some brightness settings the 2709W emits some noise/humming which is noticeable in front of the monitor. They are not as bad as with the 245b, but they are there. What saves the 2709W for me is that it is silent at brightness settings 0 and 50. These are exactly the two levels which are important for me. Obviously, complete silence over all levels would be preferable – but since none of the 4 flat screens which I have tested (Samsung SyncMaster 245b, 226bw, Dell 2407WFP and 2709W) yet could offer that, I’m starting to believe that this is not possible with current back lighting technology (looking forward to LED-backlights…).
People who are as sensitive to noise as I am should still be cautious. My experience with several 245b models has shown me that the silent brightness varies can vary strongly with each specimen. I do not know if it also varies on the 2709W, but you should be prepared. Also, reviews are usually hardly reliable when it comes to noise, since the noise perception depends on too many factors (hearing power, room acoustics, spread for standard factory models …).