Dell 2405FPW Input Lag

gustep12 said:
Hi everyone,

I guess there may be truth to several of the things said here. First of all, analog devices (CRTs) work in real time, LCDs on the other hand do a lot of things due to their digital signal processing, such as scaling, receving DVI signals, etc.

Varying signal latency can be due to slower DSPs on some LCDs - I think the 2405fpw simply has a slower DSP than it should.

It makes sense that the signal processing load (and hence signal latency) can be reduced by going to native resolution - now the DPS doesn't need to do the interpolation & smoothing anymore. On a CRT, this happens simply due to the beam / shadow mask design, but on an LCD you need to compute it all.
Click to expand...

Most well thought out response I have seen yet on the issue. This would explain why the 2405 is so bad at doing non-native rez, it has a dsp unit that is poor at this type of operation. It's probably one of the reasons the monitor is so cheap for it's size and visual quality.

Lesson is...don't buy this monitor for gaming unless your video card can do high resolutions (1920x1200) at a decent framerate.
 
navicon said:
Most well thought out response I have seen yet on the issue. This would explain why the 2405 is so bad at doing non-native rez, it has a dsp unit that is poor at this type of operation. It's probably one of the reasons the monitor is so cheap for it's size and visual quality.

Lesson is...don't buy this monitor for gaming unless your video card can do high resolutions (1920x1200) at a decent framerate.
Click to expand...

Mine has none of the mentioned lag at lower resolutions. I am very sensitive to these sorts of things and would notice. I tend to play at lower resolution than the native 1920x1200 because I like v-sync and the framerate at a rock solid 60. I've got a x800xt pe if that makes a difference, I wonder if the people with this problem have anything in common?
 
I'm glad to see this issue hasn't faded from everyone else's mind. I still hold out a shred of hope of this being fixed.

I see it as one of two things - either the way some people's brains are wired or of the monitor itself. Or both. Either way, over time the problem seems to fade away over time, but when you think about it again, it's noticeable.


However, there is NO denying this is a problem for some people. Here's some video evidence:
http://media.putfile.com/Movie_0001914

As for me, I have my computer hooked up with DVI and have an mx1000, and like many (if not all) of you I get the lag. To lend credence to the "it's definitely the monitor" problem, I have a dreamcast/xbox hooked up in VGA and Component, respectively. Still get the lag no matter which input I'm using.



So what to do? Voice our opinions to Dell and don't stop.
http://forums.us.dell.com/supportfo...essage.id=47652&view=by_date_ascending&page=1

Just keep bumping it if you wish, the board is extremely poorly moderated that it's the only way to gain any recognition. Dell themselves, no surprise, have kept mum/denied it so far.
 
I may have missed this, but do you have the mouse plugged into the LCD or the computer?

If it's the LCD, I would switch it to the machine...
 
What a curious thread!

How can one measure this lag? To notice a lag of 10 mS, one would have to be refreshing the screen at least 100 times per second. The 2405FP supports a max refresh of 76 Hz.

DVI is a fully digital signal, isn't it? So why would a DSP be involved at all? Why isn't the panel just reading the DVI provided bits and putting them on the panel? DSPs work on analogue signals. A DSP on analog inputs? Sure -- but is there really one involved on the DVI input?

Here's a block diagram from Analog Devices showing the front-end of a dual-interface LCD panel. Note the lack of a DSP: http://www.analog.com/en/content/0,2886,765%5F%5F6981,00.html

This very old PDF (from 1995!) shows a HP design for a primitive panel. DVI wasn't invented yet, so they're just using analog inputs. http://www.hpl.hp.com/hpjournal/95aug/aug95a8.pdf

Color me skeptical.
 
mikeblas said:
What a curious thread!

How can one measure this lag? To notice a lag of 10 mS, one would have to be refreshing the screen at least 100 times per second. The 2405FP supports a max refresh of 76 Hz.

DVI is a fully digital signal, isn't it? So why would a DSP be involved at all? Why isn't the panel just reading the DVI provided bits and putting them on the panel? DSPs work on analogue signals. A DSP on analog inputs? Sure -- but is there really one involved on the DVI input?

Here's a block diagram from Analog Devices showing the front-end of a dual-interface LCD panel. Note the lack of a DSP: http://www.analog.com/en/content/0,2886,765%5F%5F6981,00.html

This very old PDF (from 1995!) shows a HP design for a primitive panel. DVI wasn't invented yet, so they're just using analog inputs. http://www.hpl.hp.com/hpjournal/95aug/aug95a8.pdf

Color me skeptical.
Click to expand...

Well I don't know about any accurate measurements, but I've used the monitor with and without the lag. It seems to be from different reasons though. Mine was a driver conflict of some kind that I was able to fix. Other people get it when they use a lower resolution than the monitors native one, I've never experianced that. I've played quite a few games at 1280x800 with none of the lag I had before messing with my mouse drivers. Other people only get it when running dual displays. I've also had all sorts of different input devices plugged into the monitor from mice to gamepads and joystick with no lag, while other get lag from that also.

The only thing I can think of is that there's some cheap parts in the monitor that don't work the correctly on all systems.
 
apathypuff said:
I'm glad to see this issue hasn't faded from everyone else's mind. I still hold out a shred of hope of this being fixed.

I see it as one of two things - either the way some people's brains are wired or of the monitor itself. Or both. Either way, over time the problem seems to fade away over time, but when you think about it again, it's noticeable.


However, there is NO denying this is a problem for some people. Here's some video evidence:
http://media.putfile.com/Movie_0001914

As for me, I have my computer hooked up with DVI and have an mx1000, and like many (if not all) of you I get the lag. To lend credence to the "it's definitely the monitor" problem, I have a dreamcast/xbox hooked up in VGA and Component, respectively. Still get the lag no matter which input I'm using.



So what to do? Voice our opinions to Dell and don't stop.
http://forums.us.dell.com/supportfo...essage.id=47652&view=by_date_ascending&page=1

Just keep bumping it if you wish, the board is extremely poorly moderated that it's the only way to gain any recognition. Dell themselves, no surprise, have kept mum/denied it so far.
Click to expand...

That video shows the EXACT same lag I was getting with my 2001FP & CRT running side by side ..The fact that the lag disappeared when I ran two CRT's side by side pretty much proves the lag exists in the LCD itself.
 
navicon said:
When I first played BF2, I was running at 1024x768. I was like "omg" it's so laggy. I would turn to the left, and it would finally turn to the left like 1-2 seconds later. It was completly unnaceptable, and I was ready to return my display. I tried the native rez hack for BF2, and VOILA!! No lag.

Most new games either support widescreen, or have script/executable path hacks to enable the features. Do a google search, you'll find some good sites that list these settings.

Hope this was informative, and hopefully this will end allot of th speculation.
Click to expand...

I tried googling "BF2 native res hack" and didn't get any results pertaining to how to do the hack. Can you enlighten me/us?
 
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