I react very sensitive to flicker. Almost all modern 24 "monitor with LED backlight (with one exception) adjust the brightness via pulse width modulation (PWM), ie by the backlight on and off in rapid succession is -. A strobe effect which significantly impacted the visual center is precisely the LED backlights with its rapid response to follow so the PWM clocking immediately, while the older backlight technologies mitigate the effect by their Trägkeit. At too low a PWM frequency (eg Dell UltraSharp U2412M) is the eyes and a lot of people can do it perceive. The Dell immediately went back, completely unbearable for me.
The HP ZR2440w I bought as next because I read in reviews that it uses a very high PWM frequency and the flicker was no longer visible to the naked eye. Is also true, it is no longer visible, but it calls for me within half an hour burning headache forth. Also I can not stand long. Even so HP went back, with regret, because otherwise I found him well. The price-performance ratio is great!
Landed happy I am finally on the Eizo EV2436WFS. It is currently the only 24 "16:10 LED backlight monitor on the market, the analogy its brightness, thus governs without PWM. At least 20% down, but that is enough. So I have a totally stable image and can without discomfort work. That's otherwise currently only available for a few 27 "panels.