Dell 2408WFP Mouse Pointer Lag - Explain This

[silverglider]

About input lag and mouse pointer, I'm confused here..

Do the following:

Drag a window around, or simply drag a selector rectangle around a desktop. Watch closely how mouse pointer lags behind edge of window, title or other reference point close to moving pointer. It is very noticable how pointer lags behind. Or you scroll down a long internet page (like those on this thread) by picking the edge of slider and move up-down. Pointer lag is obvious.

Now, either I misunderstood how input lag happens or this doesn't have any logic. I mean, how it's possible that only mouse pointer lags behind but not the dragged content as well?

Furthermore, on my 2408WFP mouse pointer lags more in lower part of screen than on upper half, towards the top of the screen (im using mosly left-right movement to test)

And now the pinnacle of my confusion: Pick any icon from desktop and drag it around. Not only that lag seems to be almost gone, but pointer refreshes much faster!?

I'm sensitive to mouse behaviour, the moment I plugged a 2408 five days ago to replace my old 22' CRT I was shocked how floaty mouse pointer felt, I'm getting used to it now but still can't find any reasonable answer to the behaviour I described. I wish if you could try to replicate this and if someone more knowledable than me offers an explanation.

 

[xtknight]

It may be that different colors update at different speeds on an LCD. When you were moving the window maybe the white cursor was on a dark blue background. Perhaps your desktop is bright green and the white cursor is faster here, but that's just a guess. It would have to be some sort of illusion. There's nothing about the LCD that's slowing down only a mouse cursor.

Or, maybe it is so fast on the CRT that you can't even tell the difference.

 

[ToastyX]

You are talking about two different lags here.

The pointer lagging behind the window is normal when using a hardware cursor, at least with NVIDIA cards, and it lags behind more towards the bottom of the screen because the position of the hardware cursor is only updated between refreshes. That's because of the video card, not the monitor. Although you can see it, it's actually less than one frame of lag. You can get rid of that lag in Windows XP by moving the graphics troubleshooting slider one notch to the left, which will disable the hardware cursor and use a software cursor. In Windows Vista, that option is not available when the NVIDIA drivers are installed, but with Aero, the window will lag along with the mouse pointer since the output is vsynced, so they will appear to be synchronized. This stuff is not a problem in games since they handle the mouse movements directly.

That's not the input lag people have been talking about, although both lags add up. The floaty feeling you described is the input lag, although I'd rather see it called output lag since it's really the monitor delaying the output, which makes the input feel laggy. From what I've read, the Dell 2408WFP has a huge amount of lag, like around four frames, which is over 65 ms. That's why the mouse feels like slush. You shouldn't put up with that crap. I recommend returning it and getting a DoubleSight DS-263N instead. That monitor has almost no lag.

 

[silverglider]

You are talking about two different lags here.

The pointer lagging behind the window is normal when using a hardware cursor, at least with NVIDIA cards, and it lags behind more towards the bottom of the screen because the position of the hardware cursor is only updated between refreshes. That's because of the video card, not the monitor. Although you can see it, it's actually less than one frame of lag. You can get rid of that lag in Windows XP by moving the graphics troubleshooting slider one notch to the left, which will disable the hardware cursor and use a software cursor. In Windows Vista, that option is not available when the NVIDIA drivers are installed, but with Aero, the window will lag along with the mouse pointer since the output is vsynced, so they will appear to be synchronized. This stuff is not a problem in games since they handle the mouse movements directly.

That's not the input lag people have been talking about, although both lags add up. The floaty feeling you described is the input lag, although I'd rather see it called output lag since it's really the monitor delaying the output, which makes the input feel laggy. From what I've read, the Dell 2408WFP has a huge amount of lag, like around four frames, which is over 65 ms. That's why the mouse feels like slush. You shouldn't put up with that crap. I recommend returning it and getting a DoubleSight DS-263N instead. That monitor has almost no lag.

SPOT ON!

Thank you. Though I still don't understand how simply switching the monitor could have triggered this.. turning off hardware acceleration brought back my pointer to a responsive state as it was on my CRT monitor. I know it shouldn't have to do anything with monitor but thats what happened, the very moment i plugged 2408WFP my pointer started to lag and float - turned off cursor acceleration and its back. Im buying 8800GT these days so it might work with cursor acceleration turned on, will see.

I'm almost inclined to think some people that complained on terrible mouse lag had the same type of problem.

Ofcourse, some minor lag is still there due to notorious input lag but this is actualy completely acceptable.

Anyway, you are spot on with your explanation, thank you. You saved my day.

 

[zzz]

moving the graphics troubleshooting slider one notch to the left, which will disable the hardware cursor and use a software cursor.

You always impress me with your knowledge, ToastyX. What other consequences are there with decreasing the accerlation notch by one, and does that affect gaming performance? That's dumb that they made it so that the full acceleartion hurts mouse performance.

Dell is so lame; every new model has worse lag!
3007WFP-HC: 11.5ms
3008WFP: 46.6ms

2407WFP: 23.7ms
2407WFP-HC: 34.1ms
2408WFP: 69ms

I'm a happy owner of the 3007WFP-HC. 69ms is absolutely insane.

 

[kleox64]

You always impress me with your knowledge, ToastyX. What other consequences are there with decreasing the accerlation notch by one, and does that affect gaming performance? That's dumb that they made it so that the full acceleartion hurts mouse performance.

Dell is so lame; every new model has worse lag!
3007WFP-HC: 11.5ms
3008WFP: 46.6ms

2407WFP: 23.7ms
2407WFP-HC: 34.1ms
2408WFP: 69ms

I'm a happy owner of the 3007WFP-HC. 69ms is absolutely insane.

its the world record though, surely that counts

 

[ToastyX]

What other consequences are there with decreasing the accerlation notch by one, and does that affect gaming performance?

I haven't seen it affect anything else. Games aren't affected.

 

[silverglider]

Well, it does affect 3d and CAD applications a lot, and thats what i do

Searched on net and found quite a few people complaining about lag right after attaching lcd monitor, and just like me, turning off "hardware acceleration" solved it. Too small sample to conclude anything but its almost always either Samsung or Dell.

Today I tried whatever not to get it work with hardware acceleration and failed. The only thing i haven't tried is bringing back CRT on desk to see what will happen. I'ts over 80 pounds and I have herniated disk, so thats the last thing I'll try for sure

I will reinstall Windows first, than plug new GK.. something has to work..

 

[Dogboy714]

I'm so glad I picked up the 3007WFP-HC when I did. They will never make a decent LCD again, what with the dying off of IPS monitors & the additional lag of scalers...

 

[DremoraLord]

Firstly, thanks a lot ToastyX who seems to be the only person on the internet who knows about this hardware acceleration fix.

I turned acceleration completely off, and the mouse is much more responsive. 1 notch to the left doesn't seem to help however, which might suggest the problem is deeper down in my system?

Silverglider, what system do you run, as maybe this might affect the hardware acceleration. The system I have running my 2405fpw (also has the lags) is a AMD 3500+, XP Home, and a ATI X800 XT PE AGP, with only one DVI slot. Just had me thinking that maybe the card couldn't handle the res of the 24" via DVI, and so the acceleration is maybe not working as it should. CRTs always worked fine via the D-SUB port.

 

[DremoraLord]

Just tested my 2405fpw with my 8800gtx sli rig, and the lag is gone with acceleration set to max so I guess it was a driver/graphic card issue. As ToastyX says I cant lower it as I have Nvidia drivers on Vista

 

[slithy]

So I too got tricked into the 2408wfp and it's pointer lag bullshit. What I don't understand is how turning off a hardware accelerated cursors improves the situation, but sure enough I disabled it on my rig and the pointer doesn't feel as nearly as floaty and heavy as before (though it still does to some degree). My mouse is a razer copperhead BTW.

 

[silverglider]

I tried plugging back CRT and tried few others so I have to correct myself on few points.

Certain mouse lag caused by graphic card seems to always exists, regardless of monitor type or whatever. It is only totaly imperceptible on CRT. Its hard to measure it but i guess its about 10-15ms. It is a non question on CRT and low input lag LCD monitors, but with 2408wfp you are adding this lag on already huge 60ms of lag and that is very noticable. When you turn hardware acceleration off it feels more responsive because you are back to 60ms, without added lag from graphic card. But it is only comparitevly better, 2408wfp is laggy as hell by design and there is nothing that can be done about it.

I picked up a good link from other forum which allows you to set a delay in ms and than see how mouse responds, and also shows delay with two rectangular boxes showing up, from which the right one will be delayed by the amount you set. Ofcourse, if you are viewing that link on 2408wfp you are already starting off with about 60ms of delay so you should add it to the delay you set. But for you with CRT monitors it may be a good test, set it to around 60 and if it bothers you forget about buying 2408wft, if you can live with it go on, 2408wfp actually has pretty decent picture.

http://img228.imageshack.us/my.php?image=mouselaggn6.swf

 

[lobski]

I have bought this monitor, and yes, the mouse lag in Window is horrible. Thats almost enough reason for me to return it, but it also has the green tint problem.

You can see the green tint problem here:
http://www.hardforum.com/showpost.php?p=1032474081&postcount=697

I am hoping, really hoping that the mouse lag is fixable via software. I was going to trade this in and get a Doublesight 26", but it's 800:1 will affect me, I think.

 

[silverglider]

I am hoping, really hoping that the mouse lag is fixable via software.

Even if it's possible I doubt they will do it. If you read Dell official forums they pretty much don't give a jack about input lag. They never tested monitors for input lag, they likely never will.