Why optimal stteings arent the recommended?

[thekey]

I own a 17´ LCD, the top resolution and refresh rates are 1280x1024 and 75hz. I dont get why the recomended refresh rate is 60hz. Is it because of overusing?

 

[Fox5]

I'm not sure why.
I'd imagine one reason is that movies run in multiples of 30 (most of the time) and 75hz is not a multiple of 30.
Besides that, I think there's a DVI bandwidth limitation that prevents 75hz from being used at all resolutions.

 

[BRiT]

Typically the max resolution and max refresh rate do not occur at the same juncture due to Pixel Clock limitations.

For instance, have a look at the Dell 2007 LCD specs, notice how the Max Res is limited to 60Hz, while the lower res can hit the Max Refresh.

VESA, 1280 x 1024 @60.0 Hz = 108 Mhz Pixel Clock
VESA, 1280 x 1024 @75.0 Hz = 135 Mhz Pixel Clock
VESA, 1680 x 1050 (Digital) @59.9 Hz = 119 Mhz Pixel Clock
VESA, 1680 x 1050 (Analog) @60.0 Hz = 146 Mhz Pixel Clock

 

[Npl]

I own a 17´ LCD, the top resolution and refresh rates are 1280x1024 and 75hz. I dont get why the recomended refresh rate is 60hz. Is it because of overusing?

I guess its because you cant see a difference between 60 and 75Hz on LCDs, aslong you dont play Games which match or exceed that rate (I think even 30Hz or less would be perfectly fine for most uses). Theres no "flicker" on lower Refreshrates like with CRTs.

 

[thekey]

I guess its because you cant see a difference between 60 and 75Hz on LCDs, aslong you dont play Games which match or exceed that rate (I think even 30Hz or less would be perfectly fine for most uses). Theres no "flicker" on lower Refreshrates like with CRTs.

No that isnt correct, the monitor would refresh with a previous frame anyway.

 

[thekey]

I'm not sure why.
I'd imagine one reason is that movies run in multiples of 30 (most of the time) and 75hz is not a multiple of 30.
.

So what it would look smoother anyway.

Besides that, I think there's a DVI bandwidth limitation that prevents 75hz from being used at all resolutions.

My monitor is VGA.

 

[thekey]

Typically the max resolution and max refresh rate do not occur at the same juncture due to Pixel Clock limitations.

For instance, have a look at the Dell 2007 LCD specs, notice how the Max Res is limited to 60Hz, while the lower res can hit the Max Refresh.

VESA, 1280 x 1024 @60.0 Hz = 108 Mhz Pixel Clock
VESA, 1280 x 1024 @75.0 Hz = 135 Mhz Pixel Clock
VESA, 1680 x 1050 (Digital) @59.9 Hz = 119 Mhz Pixel Clock
VESA, 1680 x 1050 (Analog) @60.0 Hz = 146 Mhz Pixel Clock

The specifications sheet of my monitor says it SUPPORTS 1280x1024x75, yet recomended 1280x1024x60

 

[KimB]

There's not much reason to run at higher refresh than 60Hz on an LCD. Since there's no flicker on an LCD display, and since LCD displays typically can't change their colors faster than 60Hz anyway, running higher just doesn't make sense.

If it's recommended to run at 60Hz over 75Hz, it's conceivable that running at a higher refresh can shorten the life of the display, but I really don't know if that's true or not with LCD's. Still, I see no reason to run it higher.

 

[thekey]

There's not much reason to run at higher refresh than 60Hz on an LCD. Since there's no flicker on an LCD display, and since LCD displays typically can't change their colors faster than 60Hz anyway, running higher just doesn't make sense.

If it's recommended to run at 60Hz over 75Hz, it's conceivable that running at a higher refresh can shorten the life of the display, but I really don't know if that's true or not with LCD's. Still, I see no reason to run it higher.

How about alleviating the "ghost" effect? Speciallt with FPS games, I saw quite an improvement.

 

[Npl]

No that isnt correct, the monitor would refresh with a previous frame anyway.

I dont get what you mean.

Refreshrate means how often the monitor redraws its display. If you display a static image a CRT still needs high refreshrates to avoid flicker (as the displayed pixels fade away), while on a LCD refreshrate wont matter in that case (pixels are static until explicitely changed).
So unless you have fast-paced Games theres no need for high refreshrates - and even in that case its questionable you have to exceed 60Hz.

Edit: I would love to have an 50Hz Mode on my LCD for some old 2D-Scrollers. Sucks to play them when every 10 frames there is a small hickup

 

[thekey]

I dont get what you mean.

Refreshrate means how often the monitor redraws its display. If you display a static image a CRT still needs high refreshrates to avoid flicker (as the displayed pixels fade away), while on a LCD refreshrate wont matter in that case (pixels are static until explicitely changed).
So unless you have fast-paced Games theres no need for high refreshrates - and even in that case its questionable you have to exceed 60Hz.

Edit: I would love to have an 50Hz Mode on my LCD for some old 2D-Scrollers. Sucks to play them when every 10 frames there is a small hickup

You dont need to have 60 fps to have a refresh rate of 60hz, the display would be refreshed enough times with the 30 frames.
It helps in FPS where you need high framerates and there is much ghosting

 

[Npl]

You dont need to have 60 fps to have a refresh rate of 60hz, the display would be refreshed enough times with the 30 frames.

Err.. that was kinda the point of my first post, and thats why I dont understand what you meant with 'No that isnt correct'

It helps in FPS where you need high framerates and there is much ghosting

Ghosting appears because the LCDs cant switch state fast enough, its irrelevant if you change the frame 60 times a second or 100. Once a pixel changes state it needs a specific time to do the transistion.

 

[thekey]

Err.. that was kinda the point of my first post, and thats why I dont understand what you meant with 'No that isnt correct'

.

You said it would be the same for most games with 30hz. It wouldnt, it would be much less smooth, specially for FPS.

 

[Pete]

Movies are 24fps. PAL TV is 25Hz. NTSC TV is 30Hz. (All ~.)

If your LCD has Feed Forward, upping the refresh to 75Hz may reduce the lag b/w receiving and displaying an image.

Most monitor recommendations are bollocks. My 19" CRT recommends 1280x1024. Dell's circular lists the optimal res on their 2405FPW as 1680x1050. The hell, I say.

 

[Fox5]

Movies are 24fps. PAL TV is 25Hz. NTSC TV is 30Hz. (All ~.)

If your LCD has Feed Forward, upping the refresh to 75Hz may reduce the lag b/w receiving and displaying an image.

Most monitor recommendations are bollocks. My 19" CRT recommends 1280x1024. Dell's circular lists the optimal res on their 2405FPW as 1680x1050. The hell, I say.

Err, isn't that the max res of the LCD?
As for CRTs, there is a limit to what resolution + refresh rate they can do before clarity is lost, and often the scanning rate can be higher than what the screen can physically resolve so you end up with overlapping pixels. In effect, a crappy sort of super sampling.

 

[BRiT]

Err, isn't that the max res of the LCD?

The max res of the 2405 is 1920x1200@60Hz.

 

[Fox5]

The max res of the 2405 is 1920x1200@60Hz.

Maybe that other res is the highest that VGA or some older DVI cards can deliver then?

 

[BRiT]

Maybe that other res is the highest that VGA or some older DVI cards can deliver then?

Nope. The unit can do 1920x1200@60Hz even when using the Analog VGA connector. Of course it looks better on the DVI connector. Even the 9700 series supports both the max res using DVI or VGA. I have no idea why they list anything other than the native resolution as the optimal resolution.

 

[poopypoo]

Most monitor recommendations are bollocks. My 19" CRT recommends 1280x1024. Dell's circular lists the optimal res on their 2405FPW as 1680x1050. The hell, I say.

I agree... I've been using Windows or 3rd party apps to force whichever refresh rate looks best to my tired eyes since ~1998, and I have yet to lose a monitor prematurely. Well, I DID melt one back in 2000, but it was one I'd bought 2nd-hand from a somewhat shady roommate, so I'm NOT surprised. Even though I'm not the type to spend more than $350 on a monitor, I'd hate to lose one prematurely... but I buy them to deliver the sharpest, most comfortable image I can afford -- so that's what I'll try and get out of them.