jasonpicard Yeah I've never had the problem of the ache-behind-the-eyeballs and sharp headache with CCFL-backit LCD monitors (aside from eventually getting eye strain due to using it too much!).
However, I do keep the brightness at 0%, the "Preset Mode" on my OSI menu to "Warm", and I also run f.lux @ 5000K at all times. If I reverse these settings and turn up the brightness, I will eventually get those sharp headaches and aching eyeballs, but it will take longer to set in (hours instead of minutes with an LED-backlit).