DVI Refresh Rate

I've a FX5600 card and a Viewsonic VG712s LCD. The
connection is thru DVI-D. And running Win2K and latest
official Nvidia driver. I've only able to run at 60Hz
refresh rate, is it normal?

If I change the connection to VGA (thru the Dsub-15
connector), I can run the refresh rate up to say 100Hz.

In all case, the resolution is 1280x1024 (the native
resolution of the LCD).

Can anyone enlighten me, which is the limiting factor in the
above setup? The FX5600 card? The TMDS encoder on the
card? The LCD? The driver?

Just want to know the "behind reason".

Stephen SM Wong @ Hong Kong.

Yep this sounds about normal really. What is the refresh rate of your
LCD?

The highest I have seen is only 75.

Stephen SM WONG wrote in
phen.com:

I've a FX5600 card and a Viewsonic VG712s LCD. The
connection is thru DVI-D. And running Win2K and latest
official Nvidia driver. I've only able to run at 60Hz
refresh rate, is it normal?

If I change the connection to VGA (thru the Dsub-15
connector), I can run the refresh rate up to say 100Hz.

In all case, the resolution is 1280x1024 (the native
resolution of the LCD).

Can anyone enlighten me, which is the limiting factor in the
above setup? The FX5600 card? The TMDS encoder on the
card? The LCD? The driver?

Just want to know the "behind reason".

Stephen SM Wong @ Hong Kong.

Haven't used an LCD for a while but when I did the refresh rate was fixed
at 60Hz for pretty much all LCD's. I'd bet that is still true.

"Stephen SM WONG" wrote in message
phen.com...
I've a FX5600 card and a Viewsonic VG712s LCD. The
connection is thru DVI-D. And running Win2K and latest
official Nvidia driver. I've only able to run at 60Hz
refresh rate, is it normal?

If I change the connection to VGA (thru the Dsub-15
connector), I can run the refresh rate up to say 100Hz.

In all case, the resolution is 1280x1024 (the native
resolution of the LCD).

Can anyone enlighten me, which is the limiting factor in the
above setup? The FX5600 card? The TMDS encoder on the
card? The LCD? The driver?

Just want to know the "behind reason".

Stephen SM Wong @ Hong Kong.

It's usually fixed at 60Hz, because LCDs don't truly "refresh" like CRTs do.
There's no flickering on an LCD, so you don't really need to worry about the
refresh at all.

Refresh rates on LCDs are almost all 60Hz. Its not like a CRT where a
refresh of 60Hz will give you a headache. You should leave it at its native
res and refresh or you will adversely affect picture quality. I would guess
its not acutally doing above 60Hz its just telling you thats what the video
card is sending and then converting it back down to 60Hz internally. By the
way use DVI-D if you can it gives alot sharper picure over all.


"Stephen SM WONG" wrote in message
phen.com...
I've a FX5600 card and a Viewsonic VG712s LCD. The
connection is thru DVI-D. And running Win2K and latest
official Nvidia driver. I've only able to run at 60Hz
refresh rate, is it normal?

If I change the connection to VGA (thru the Dsub-15
connector), I can run the refresh rate up to say 100Hz.

In all case, the resolution is 1280x1024 (the native
resolution of the LCD).

Can anyone enlighten me, which is the limiting factor in the
above setup? The FX5600 card? The TMDS encoder on the
card? The LCD? The driver?

Just want to know the "behind reason".

Stephen SM Wong @ Hong Kong.

Oh, thank you for all those who had replied in this
newsgroup. I do find 60Hz refresh rate satisfactory on LCD,
just curious to know how come the VGA signal and DVI signal
will have different refresh rate limits.

Wish you all a Happy New Year!

Stephen SM Wong @ Hong Kong.

On Thu, 30 Dec 2004, Jim wrote:

Refresh rates on LCDs are almost all 60Hz. Its not like a CRT where a
refresh of 60Hz will give you a headache. You should leave it at its native
res and refresh or you will adversely affect picture quality. I would guess
its not acutally doing above 60Hz its just telling you thats what the video
card is sending and then converting it back down to 60Hz internally. By the
way use DVI-D if you can it gives alot sharper picure over all.


"Stephen SM WONG" wrote in message
phen.com...
I've a FX5600 card and a Viewsonic VG712s LCD. The
connection is thru DVI-D. And running Win2K and latest
official Nvidia driver. I've only able to run at 60Hz
refresh rate, is it normal?

If I change the connection to VGA (thru the Dsub-15
connector), I can run the refresh rate up to say 100Hz.

In all case, the resolution is 1280x1024 (the native
resolution of the LCD).

Can anyone enlighten me, which is the limiting factor in the
above setup? The FX5600 card? The TMDS encoder on the
card? The LCD? The driver?

Just want to know the "behind reason".

Stephen SM Wong @ Hong Kong.

I honestly have no idea why the VGA connection offers extra refresh rates.
From what i understand the LCD really only outputs 60Hz anyway. Maybe its
for compatability.
"Stephen SM WONG" wrote in message
hen.com...
Oh, thank you for all those who had replied in this
newsgroup. I do find 60Hz refresh rate satisfactory on LCD,
just curious to know how come the VGA signal and DVI signal
will have different refresh rate limits.

Wish you all a Happy New Year!

Stephen SM Wong @ Hong Kong.

On Thu, 30 Dec 2004, Jim wrote:

Refresh rates on LCDs are almost all 60Hz. Its not like a CRT where a
refresh of 60Hz will give you a headache. You should leave it at its
native
res and refresh or you will adversely affect picture quality. I would
guess
its not acutally doing above 60Hz its just telling you thats what the
video
card is sending and then converting it back down to 60Hz internally. By
the
way use DVI-D if you can it gives alot sharper picure over all.


"Stephen SM WONG" wrote in message
phen.com...
I've a FX5600 card and a Viewsonic VG712s LCD. The
connection is thru DVI-D. And running Win2K and latest
official Nvidia driver. I've only able to run at 60Hz
refresh rate, is it normal?

If I change the connection to VGA (thru the Dsub-15
connector), I can run the refresh rate up to say 100Hz.

In all case, the resolution is 1280x1024 (the native
resolution of the LCD).

Can anyone enlighten me, which is the limiting factor in the
above setup? The FX5600 card? The TMDS encoder on the
card? The LCD? The driver?

Just want to know the "behind reason".

Stephen SM Wong @ Hong Kong.

I honestly have no idea why the VGA connection offers extra refresh rates.
From what i understand the LCD really only outputs 60Hz anyway. Maybe its
for compatability.

My Iiyama E435S does exactly the same. ie. I can set 75hz as recommended when
using the vga cable but it sets it to 60hz when my DVI-DVI cable is used.

IME I actually did'nt notice any significant improvement by purchasing the DVI
cable... not that the picture could get much sharper. :-))))

Mike

I voluntary to try

You need to know 3 things to understand!
1. How your eye(s) and brain work (partly)
2. How CRT work (partly)
3. How LCD work (partly)
4. How we define the term "Digital" and "Analogue" (partly)

1. When our eye receive a signal, our brain will store it for something
like 1/30 ( I don't know the exact figure) of a second. So, if you switch a
light on and off faster than 30 times per second, your brain will fool you
that the light is continuous. If you do it slower, you will not just see the
light on and off, but you are going to get a headache very soon as well.
Somehow this "headache" business remain until we see the light switching on
and off faster than 70 times per second.

2.The CRT is an analogue device, it work like the electron gun send a beam
of electrons to the phosphorus coated screen, when the phosphorus hit by
electrons, it glow and more(stronger) it glow brighter, no electron? No
glow! Therefore, the electron gun was quite busy to "sweep" through the
whole screen to generate a picture AND re-hit the same phosphorus to keep
them glow to maintain the picture. The rate it "sweep" through the whole
screen is call the refresh rate. As in 1, it require the refresh to be 30Hz
to fool our brain it's not glowing on and off but at this rate, it give us
headache. Increase the rate to 70Hz or high, it made us more conformable to
"see" a "illusion" of a picture!

3.LCD display is digital device. The colour LCD itself do not glow, it
require a backlight (fluorescent lamp) to be seen. When LCD is "off", it is
transparent, when you pass it with electricity aka "on", it change colour.
Each LCD in the display has its own circuit to control the on/off. That's
how LCD work. If you keep the backlight continue on, you just switch
different LCD to "on" to maintain the picture, no "refresh" require.

4. Any thing can be represent in 1 & 0 only can be translate to "ON" & "OFF"
and vice versa are define as "digital". Everything else are "Analogue".

Now the video card is working in a digital domain, simply send the digital
signal through the DVI interface to control each LCD's on/off to create a
"picture". It (almost) has nothing to do with refresh rate!
But the CRT is different, the video card have convert digital signal (on &
off) to analogue signal (VGA) to control the amount (how many/intensity) and
the duration (how long) of electrons hitting the phosphorus and "refresh"
everything for 70 times or more per second to generate a stable "illusion"
of a picture.

The availability of the refresh depend on 2 things, the D/A (digital to
analogue)converter on the video card and how good is the electron gun inside
the CRT.

I really don't know what the refresh rate setting in LCD for @@"

But I knew one thing, to display a series of different pictures to generate
a motion picture/animation, the refresh come in matter, the maximum frame
rate (frame per second/fps) can be display is same as the refresh rate
setting of your system and the higher the frame rate the smoother the
motion.

HTH


"Stephen SM WONG"
tephen.com...
Oh, thank you for all those who had replied in this
newsgroup. I do find 60Hz refresh rate satisfactory on LCD,
just curious to know how come the VGA signal and DVI signal
will have different refresh rate limits.

Wish you all a Happy New Year!

Stephen SM Wong @ Hong Kong.

On Thu, 30 Dec 2004, Jim wrote:

Refresh rates on LCDs are almost all 60Hz. Its not like a CRT where a
refresh of 60Hz will give you a headache. You should leave it at its
native
res and refresh or you will adversely affect picture quality. I would
guess
its not acutally doing above 60Hz its just telling you thats what the
video
card is sending and then converting it back down to 60Hz internally. By
the
way use DVI-D if you can it gives alot sharper picure over all.


"Stephen SM WONG" wrote in message
phen.com...
I've a FX5600 card and a Viewsonic VG712s LCD. The
connection is thru DVI-D. And running Win2K and latest
official Nvidia driver. I've only able to run at 60Hz
refresh rate, is it normal?

If I change the connection to VGA (thru the Dsub-15
connector), I can run the refresh rate up to say 100Hz.

In all case, the resolution is 1280x1024 (the native
resolution of the LCD).

Can anyone enlighten me, which is the limiting factor in the
above setup? The FX5600 card? The TMDS encoder on the
card? The LCD? The driver?

Just want to know the "behind reason".

Stephen SM Wong @ Hong Kong.