View Full Version : Viewsonic LCD refresh rate problem

08-30-2005, 04:42 PM
I have 2 Viewsonic VP912b 19" LCDs hooked up to a computer. I have a Geforce 6600 GT video card with 2 DVI outputs and the latest drivers.

I have the drivers installed for the LCDs, they show up as "Viewsonic VP912B" in device manager. I have them running at 1280x1024, their native/maximum resoution.

Their specifications say that their refresh rate is 85 Hz at that resolution (link (http://stores.tomshardware.com/search_techspecs_full.php/masterid=4001241)) . However, when i go to Display Properties->Settings->Advanced->Monitor it shows the refresh rate as being 60 Hz. That is the only refresh rate I can choose. The "Hide modes that this monitor cannot display" checkbox is checked.

How come I cannot select 85 Hz. Would it be safe to uncheck "Hide modes that this monitor cannot display" and raise the refresh rate? When I do uncheck that box, I am given the options of 60 Hz and 75 Hz. Still no 85 Hz. Why is this? I am very confused. Thanks a lot for any help.

08-31-2005, 02:59 AM
Refresh rate means something very different for LCD screens than CRTs. On a CRT, the screen is being constantly redrawn, and a high refresh rate is crucial to avoid irritating visible flicker.

This isn't happening on an LCD - each pixel lights up the required colour, and stays lit up until it is told to change to a different colour.

The refresh rate quoted in your link is how fast an input signal the screen can cope with from an analog input. It isn't really very meaningful, since the panel itself cannot respond at that rate. 60Hz in DVI mode is typical, in fact I believe it's the highest rate the DVI interface can transmit at high resolution.

In short, there's no problem here!