Telinar, I'm not an expert on this, but it was the spec sheet that prompted me to call Samsung. Since the maximum vertical is listed as 160hz and it seemed very unlikely that the maximum refresh rate was the same from 640x480 up to 1024x768, I wondered whether what are listed as "VESA presets" in the manual represented max refresh rates. And I could see that there was a clear difference between 85hz and 100hz. Since there's a 3-year warranty on the monitor, I didn't see why Samsung would give me info that would lead me to run it out of spec. I've been doing it for about a year and a half with no problem.