Originally posted by ~*McoreD*~@Mar 3 2003, 06:15 AM
Many people mentioned the Refresh Rate as well. I didn't mentioned that before, well mine is set to 75Hz. What's the difference between a 60Hz or 75Hz or 85Hz. I can't feel it in my screen. Can anybody please explain? Thanks. 
When you see an image on your screen, it appears to the human eye to constantly cover the entire monitor. In reality an electron beam 'scans' the monitor, from top to bottom, making phosphor on the screen glow for a short period of time. At any instant only one point on the screen is at full brightness. You may have noticed this effect when a monitor screen is filmed with a camera. You get bright flickering stripes accross the screen as the camera takes a short snapshot for each frame.
The screen is scanned repeatedly, keeping it illuminated. Each scan is called a 'refresh'. A refresh rate of 75Hz means 75 refreshes every second. The human eye does not repond to brightness changes that quick, so you end up seeing the average brightness for each pixel, not realising that this fluctuates from very bright to very dark 75 times every second.
Whilst you will not be able to see the scanning from top to bottom, many people will be able to perceive flicker at lower refresh rates. I am used to 85Hz, and when I see a monitor set to anything below that, I can usually instantly recognise the low refresh rate. Many people are not able to notice the flicker itsself, but end up with sore eyes or discomfort when looking at low refresh rates. If looking at a screen seems unnatural to your eyes, a low refresh rate may well be the reason.
On TFT monitors this does not apply - pixels stay illuminated for much longer, the only effect of the refresh rate is that updates to the screen image are less frequent. This won't be visible except when an image changes 1/2 way through a refresh - 1/2 the screen will show an old frame, and 1/2 will show the new frame. This 'tearing' effect was mentioned here before.
Oh, and my config
1280x1024 @ 80Hz on an 19" monitor (primary)
and 1024x768 @75Hz on a 17" TFT screen (secondary)
(in a dual monitor arrangment)