View Full Version : Refresh rate question
[XC] Hicks121
02-08-2010, 07:36 AM
On LCD screens I see that there are horizontal & vertical refresh rates. How does this work when setting the refresh rate in your os? There is a pretty decent range for both on the ratings of the screens.
for eg:
Horizontal Refresh Rate 54.2-83.8KHz
Vertical Refresh Rate 49-75Hz
Can anyone help me in understanding this?
Thanks!
Hicks
Sparky
02-09-2010, 08:25 AM
You generally have no control over the horizontal, CRT or LCD.
Vertical mattered most with CRT as you had flicker at 60 and still a tad noticeable at 75. Could cause eyestrain and all that. LCD doesn't matter as much in that regard as it doesn't work the same as CRTs did. Now what you are limited to at 60Hz "vertical" on an LCD is how many frames you can get displayed per second. So if you were at say 90fps you wouldn't see 30 of those. That can sometimes lead to tearing where the LCD refreshes halfway through a video input refresh.
As far as I'm aware, 75Hz doesn't really exist on an LCD.. it is there for compatibility reasons but won't actually display 75Hz as it is "down-converted" to 60Hz for the panel. Someone correct me if I'm wrong.
[XC] Hicks121
02-09-2010, 09:08 AM
Ok, thats what I kinda thought. Why the hell do they spec it at 75htz then? morons....lol
Sparky
02-09-2010, 11:07 AM
Hicks121;4235717']Ok, thats what I kinda thought. Why the hell do they spec it at 75htz then? morons....lol
Compatibility reasons. When you're in the BIOS or in DOS mode, that is usually 70-72-75Hz somewhere in there. If the panel couldn't support that, then you'd be screwed in anything but Windows.
There are LCD units on the market that have up to 200Hz refresh rates (big $$$). My monitor will sync up to 76Hz vertical, but will display "tearing" if I feed it too much more.
STEvil
02-09-2010, 06:05 PM
There are LCD units on the market that have up to 200Hz refresh rates (big $$$). My monitor will sync up to 76Hz vertical, but will display "tearing" if I feed it too much more.
No there are not. Real the specs are where vertical refresh rate is found as listed in the first post (not often easily found..). They will all list 60hz or 60-75hz (technically 75hz is run through the onboard scaler or frame-dropped).
The few that are not limited to 60hz are TRUE 120hz and there are approximately 5 models at the moment. They are all under 25" and only 1 (maybe 2) support 1920x1080. They will list the vertical refresh rate as 60-120hz.