OCing LCDs...a good or bad thing?

[micamica1217]

I've asked in the official thread of the L90D+...
but I got no real replys.

I've noticed that the L90D+ has a 60hz refresh rate with the DVI @ 1280x1024...
but I'm able to unlock other refresh rates...it works too.

would using 70hz or 75hz HURT the LCD?

mica

[Avg]

I though that LCDs didn't really have a refresh rate because only the crt's pixels needed to be refreshed to keep the image.

[ajrettke]

it doesn't use refresh rates with DVI, set it to the max to ensure best performance, won't hurt the LCD

[filip04]

lcd's don't have a refresh rate.. in fact... each pixel stays on for as long as it doesn't get changed. whether at 60hz or 70, it won't make any difference

[micamica1217]

ok boys, please don't tell me that an LCD don't have a refresh rate...it does.
I'm quite aware of the differance between refresh rate and responce times.

whether at 60hz or 70, it won't make any difference.

oh, yes it will...at least in games with vsync turned on or not.
there will be a displayed, max frame rate differance.
(at least it should)

mica

[Albuquerque]

Mica, you know me, and I know you.

Unfortunately, they are right, there really is no refresh rate on an LCD. The entire word "refresh" used in terms of display devices means to "refresh the screen", or in other words, to repaint it. LCD's dont do that. They are a constant-on device. There is no repainting, and thus, no refreshing.

The maximum time required for an LCD element to change from full-off to full-on is it's response time. However, the LCD's response also dictates it's maximum displayable discrete frame rate. An LCD element with a response time of 14ms would be able to completely change ~70 times per second, which also gives you a maximum displayable frame rate of the same. But that's not a REFRESH rate, it's simply a function of maximum response time.

So...

"Overclocking" and LCD will net you basically zero, because you aren't limited by the electronics in the DVI port. You are instead limited by the liquid crystal technology used in the panel itself. You could overclock that thing to eight billion hertz, but the LCD elements could still only change a maximum of ~70 times per second (again, on a 14ms monitor)

[Albuquerque]

Well, I did a little more research on your specific monitor, and at least now it makes sense why you want to "overclock it". An 8ms response time on the LCD panel means you should be able to net a maximum of 125fps. So I guess now the question is, even though the panel is 8ms capable (in theory), are the electronics up to the task of feeding it data at that rate? 1280x1024 in 24 bit color at 125fps is something around 468mb/sec of data coming down that DVI port. It's quite possible the supporting electronics (or hell, even the DVI itself) can't deal with that kind of throughput.

I guess I need to go do some more research on DVI connections...

[evowatercooling]

The Average Response Time for that monitor is about 23-25ms. That would give you a "refresh rate" of about 40hz. (that is when it goes from 0 to a certain number) I would say that the average response time you will be seing should be around 16-20, which would net you about 60fps.

Besides all that crap that I just said, if you think it looks better at 70hz over 60hz. Given the fact that there is not any moving parts like in a crt, (if changing the refresh rate actually does anything) then no damage can be done to the lcd. All that will happen is that a pixel may not have fully changed to the previous color before it is asked to change again. So do whatever looks best.

And have fun with that monitor. I read the review on tomsHardware, damn nice for a 19" lcd. The only down side they said was the narrow viewing angles, which made it not the best for watching movies. I think that I might get one later. How do you like it for games? (if you play games.)

[Npetune3000]

O "OC'd" My LCD from 60mhz to 70mhz and by doing so I was able to reach higher resolutions. Unfortunately my monitor is a 17 inch but I was able to get it to 1600x1200

[evowatercooling]

Why would you want to increase the Resolution on an LCD. There are only enough pixels for 1280x1024. Increasing to 1600x1200 should not make it look better, actually it should make it worse.

[Albuquerque]

Why would you want to increase the Resolution on an LCD. There are only enough pixels for 1280x1024. Increasing to 1600x1200 should not make it look better, actually it should make it worse.
I don't even see how it's physically possible, unless the onboard electronics are somehow down-sampling your image to the native screen resolution. LCD panels have a very specific resolution and they do not change. If your LCD is natively 1280x1024, then even when you run 800x600 it will still "stretch" the image to fit onto a 1280x1024 grid of pixels.

To do this backwards (1600x1200 -> 1280x1024) would net you zero visual gain for probably ~30% performance loss. Of course, this is saying it's even possible to do...

How is the average response time on the L90D+ 25ms? Isn't it rated at 8ms? 4.8ms ramp-up and 3.2ms ramp-down is what I found, which means your maximum is 8ms.

[evowatercooling]

Go to this website (http://graphics.tomshardware.com/display/20050215/lcd-04.html). LCD manufacturers only have to display the response time for the monitors from 0-255 color. That coincidentaly is where the fastest response time is recorded. going from 0 to anything less than that tends to be slower. This does not make a monitor bad, it just means you should do you research and not buy a monitor just because it says 8ms.

[micamica1217]

sorry I didn't trust most of the original replys.
it's just that someone with this LCD (L90D+) stated that he got tearing in Doom3 with vsync turned off.
so I did all my testing with vsync turned on.
lol, what a waste...I finaly retested Doom3 with vsync turned off at both 1280x1024 and 1024x768. no tearing.

BTW, my full review is on page 2 of this thread....http://www.ocforums.com/showthread.php?t=364128
Albuquerque will tell you that I'm a bit harsh when I test things, i tend to look for faults in products.
after all, most people and review sites will already tell you all the great stuff anyway...so why not hear some of the bad things.
well the list of bad things are so small, and trivial, that I can say that "THIS IS THE LCD TO GET FOR GAMING!!!!!111one".
comming from a CRT man for the last 12 years, that has to say something.
read the review for more info...but you'll not find a better 19" LCD for gaming.



Mica, you know me, and I know you.
and that's why I trust you and your thoughts...I needed a guru that knows what he's talking about.


How is the average response time on the L90D+ 25ms? Isn't it rated at 8ms? 4.8ms ramp-up and 3.2ms ramp-down is what I found, which means your maximum is 8ms.

ok, Dupont tested this LCD at basicly 50% brightness and 50% contrast for most tests...including responce times.
he got 10ms at best, responce times.
http://graphics.tomshardware.com/display/20050215/lcd-04.html

when it comes to responce times bro, color changing can be higher then black to white.
the best reponce times were 10ms and the worst case of pixel changes were 27ms...this is normal in a LCD.
12ms panels can reach far higher...you don't want to know what 16ms responce times are truly like.
needless to say, with all games briefly tested, I get no ghosting.
not even in fast online play.
(btw, I use 75% brightness and 50% contrast...I'm sure I'm getting better responce times then the reviewer tested.)

as for the OCing part....
you see, with the D-Sub, the specs say I can use 60hz or 75hz.
yet only 60hz with the DVI port.
yet it works at 75hz with the DVI...and I think it looks better (I know, it's all in my head. then again, there are alot of things swimming in my head. lol)
I just don't want to blow $390.00...and with the price going up each day, it will cost me $500.00 for a new one, if I kill this.

mica

[sharkmont]

Interesting, I had no idea you could overclock an LCD. I might have to try this out. Is there watercooling available for this?

[covana2244]

I don't think changing the refresh rate actually changes it. Set it to 75hz then press your menu button on the monitor, it will still say 60hz.

[Midnight Dream]

I don't even see how it's physically possible, unless the onboard electronics are somehow down-sampling your image to the native screen resolution. LCD panels have a very specific resolution and they do not change. If your LCD is natively 1280x1024, then even when you run 800x600 it will still "stretch" the image to fit onto a 1280x1024 grid of pixels.

The basis of it is possible, and you are exact. I will just clarify alittle on how it works.

A standard 15" LCD is built with an exact number of pixels, usually 1024x768. This is its optimum resolution. It will have its sharpest clarity at this resolution. But you can still put it into other resolutions. How does this work? Simple. The monitor will actually somewhat combine the image to force more image pixels into one monitor pixel. That is why it appears blurry, because one of your 1024x768 pixels might be trying to force 2 or 3 image pixels in, because you are trying to put it at 1280x1024.

[sharkmont]

Oh that explains why everything looks like garbage unless my Dell 1703FP isnt at 1280 x 1024, thanks Midnight for the further info.

[Boegy3]

Hey guys, been a long time since I posted and I apologize for bringing up an old thread, but I tried messing around with the refresh rates on this monitor. What I noticed that shocked me was that the mouse sensitivity increased noticeably as I increased the "refresh rate" of the L90D+. Does this make any sense?

[amdking]

as far as refresh rates going into an LCD...I was wondering, when a manufacture specs it at say 60hz but its capable of displaying 75hz without giving a frequency too high warning on the OSD....and in regards to overclocking like the original poster stated, I know this wont change the picture hardly any because the LCD panel technology itself does not run off a refresh rate. But what about the electronic hardware, within the monitor, that translates the image to the actual LCD pixels? could it be optimal for this part of the monitor to work at 60hz rather than 75hz?

so, in theory there is an optimal setting for this as far as the electronics of the display go before it gets to the pixels.

Thats the only reason I can see...why a monitor rating from manufacture would be at 60hz and not mention anythin about 75hz.
overall ... sure yeah the LCD will run both but maybe these electronics Im speaking of work their most optimal and easiest at 60hz.

make any sense? lol

[apu318]

O "OC'd" My LCD from 60mhz to 70mhz and by doing so I was able to reach higher resolutions. Unfortunately my monitor is a 17 inch but I was able to get it to 1600x1200

First of all, its 60hz and 70hz not MHZ. There is a BIG difference.
Second, you cannot gain higher resolutions by increasing your "refresh rate". Your monitor would alwayts be able to go up to that resolution.
Third, just because in your display control panel you see higher rates and resolutions, doesn't mean they work on your monitor thought you may be able to set the setting and still have a working display.

The max refresh rate for my crt for 1280x1024 is 60hz, but I can set it to 70 and 75 and still get a working picture and do everything and see everything I normally would, however, I am still limited to 60fps in any game that I am running at that resolution with vsync on.

[amdking]

First of all, its 60hz and 70hz not MHZ. There is a BIG difference.
Second, you cannot gain higher resolutions by increasing your "refresh rate". Your monitor would alwayts be able to go up to that resolution.
Third, just because in your display control panel you see higher rates and resolutions, doesn't mean they work on your monitor thought you may be able to set the setting and still have a working display.

The max refresh rate for my crt for 1280x1024 is 60hz, but I can set it to 70 and 75 and still get a working picture and do everything and see everything I normally would, however, I am still limited to 60fps in any game that I am running at that resolution with vsync on.

hrm I was under the impression that if u run a CRT above its max refresh rate for a given resolution and it does not give you the "out of range" protection error then u risk frying ur tube.

[mcoleg]

yet it works at 75hz with the DVI...and I think it looks better (I know, it's all in my head. then again, there are alot of things swimming in my head. lol)


actually, setting refresh to 75hz refresh rate might prove somewhat beneficial... at least i think so...

i finally managed to set my 2405FPW to 75hz - in search of a way to minimize image lag in bf2, among other things i tried - and it helped a bit, at least it looks so to my eyes. as mic said, it could be just in my head but couldn't it be that the games read the refresh info from windows and adjust accordingly, even though the actuall output might not have changed?

just a theory...

[amdking]

I honestly think the only change you are going to see with changing the refresh rate on an LCD is if you have vsync enabled and that allows you to get higher FPS...period.

LCD's show no evident of any other change in pixel operation when altering the refresh rate. thats the impression Im under.

[FIZZ3]

hrm I was under the impression that if u run a CRT above its max refresh rate for a given resolution and it does not give you the "out of range" protection error then u risk frying ur tube.

Even the cheapest of monitors from ~5 years ago will simply not run a refresh that they do not support and default to an acceptable setting instead, leaving the control panel to think it was set successfully.
An unsupported resolution may be another thing though, and that can cause the screen to go black.

[TheGreySpectre]

The Average Response Time for that monitor is about 23-25ms. That would give you a "refresh rate" of about 40hz. (that is when it goes from 0 to a certain number) I would say that the average response time you will be seing should be around 16-20, which would net you about 60fps.



To my knowledge the L90+ is 8ms, thats what it has listed in the specs, however they do make a L90 non plus that has a 25ms response time