When i got this 120 Hz monitor, ACER GD245HQ - i got a lot microfreezes in Quakeworld, that appears about every ~0.7s all time in game, no matter what i doing.
Dont know why it look so bad on my monitor. I downgraded physical frequency of videocard: GPU, Memory, Shaders on minimum and found that microfreezes just become longer.

Found solution: create in nvidia panel custom resolution 1920x1080, with vertical frequency 110 Hz, and then use this in Quakeworld.

You can try decrease vertical frequency for matrix (119 -> 118 -> 117...), to find your own.

If someone can help me solve that trouble by another way, tell me please!

If using XP, disable threaded optimization (an old trick). The problem could also be caused by the very high input lag of the monitor.

Your "solution" is not really a solution, as you have to use lower than specs refreshrate to get it working properly. What if your 3GHz CPU could run only 2,5GHz? Anyway, test the monitor on another computer to be sure it's the culprit. Or maybe on some other game that has fpslimiter and you can run ~120fps (UT3, Q3, there are others) or even try using vsync.

My solution is only about to play smooth Quake, not maximize settings, if its not possible

Of course i tested monitor on another computer before i wrote here.
Disabling/enabling threaded optimization does nothing with microfreezes, same as vsync.

And about input lag - i dont feel such huge delay (50 ms, you joking ?), mb something wrong with that test or its marketing solution to sell out more old monitors before new
Anyway i dont believe in tests more, after i buy ATI, that shows good fps only in few games, but quake and wow, where it have quarter and half fps, compared to nvidia with same price.

Ah, the problem seems to affect other people too, read here (murdoc & Dash_RipRock).

how about disabling hardware temperature minitorig software?

I tried everything thats possible, its just a crappy screen. I have returned it and still waiting on a better 24" or bigger screen.

For me too late to get monitor back