I have, however, need to determine, at least for my model, a much more serious problem for me:
Once are represented as image content such as large tables (including Gmail) or long passages of text, so image content with high contrast (very dark next to light pixels many), the monitor produces a distinct hum similar to plasma, combined with a very high frequency whistle. Presumably then the circuit operates in the drive, the 6 - is responsible> 8 bit dithering, under full load and thus generates vibrations in coils.
A similar phenomenon I know from my Dell 2407, also in image content with high contrast, but in this no whistle sounds only a hum.
Mir is a mystery why Dell has given this structure in the production, especially DELL itself sells office computer, the With the latest fan technology are so quiet that one course the whistling sound heard from the monitor, if one before sitting (even at 50cm distance). I can only tell me so that the decision-makers who approved the prototype, are already at an advanced age and no longer hear so well. The typical 30's, myself included, who has his hearing not abgeschleift in discos is, in any case in the A00 revision can not concentrate with this model.
The predecessor of 2407, the DELL 2405, there was, incidentally, in the first revision as whistling sounds that have been corrected in later revisions, so far there is still hope.
Addendum of 10/10/2012:
I again tried 2 of these devices, both Rev. A00. Both had the illumination in order of yellowish / red colorations do not see anything. In both, however, was also the high-frequency whistling heard.
I have the problem can continue circling: It occurs with any setting of Contrast> 0. So if you scale down the contrast to 0, the whistling noise disappears - but also the screen is then completely black because, unlike it says intuition and labeling , governs the contrast in reality the strength of the backlight, in contrast = 0 ie the LED backlight completely. The whistling is therefore generated by the backlight.
It is further assumed that the monitor a kind of local dimming of the LEDs operate, and it analyzes the image content. Then, when image but contents are displayed, the rapid successions of white and black display (the aforementioned Excel spreadsheets, large blocks of text, GMail), believed to be the power of the LEDs is as fast varied, that the said pipes can be heard. I further noticed that apart from the pipes, the monitor generates a constant chirping, regardless of the image content, and this chirping disappears only when you provide contrast = 0 (or the monitor turns off).
In this respect, I strongly doubt the testimony of many testers, the monitor would not use PWM control for LEDs. The test methods to detect the cameras used only PWM frequencies up to 400 Hz. I suspect this unit is very well governed by PWM, but it is at a frequency above 400 Hz. The flickering is not more visible, but audible! Similar effects there are, incidentally, also with power supplies, Seasonic va whose AC-DC converters also produce a very similar whistling sound, as many laptop power adapters, including Dell.
Since I now therefore 3 devices had here and all 3 have the same defect, it will probably be a general design flaw in Rev. A00. Too bad.
