I've learned my lesson on input latency and pixel response

Dankk

Diamond Member
Jul 7, 2008
5,558
25
91
For many of you, this is already common knowledge. I apologize for that. This is a short anecdote from someone who had to learn it the hard way.

It started a few weeks ago when I found a deal on refurbished AOC-brand I2757FH 27" AH-IPS monitors for only $190. Although my old 23" Asus TN monitor had been serving me well for some time, I'd been looking to upgrade to something bigger and better-looking. IPS monitors have become pretty cheap too. I figured that an upgrade was finally in order, and grabbing a pair of the I2757FH's would be a fine choice.

I was skeptical about latency. I do vaguely remember hearing that IPS panels are at a slight disadvantage to TN panels in that particular area. Video games are important to me, and I consider myself very sensitive to input lag, so I wanted to make sure I was getting an IPS panel with as little lag as possible. Fortunately, the AOC was advertised as having only "5 MS (GTG)" response time. That sounds pretty decent, right?

Wrong. Upon hooking up my new monitors and using them for the first time, something definitely felt "off" about them. They looked great, that's for sure. But I felt like there was just a tiny bit more delay than I was used to... and that was just when I was moving my mouse cursor around in desktop mode. I told myself that maybe it was psychological; that maybe, that extra 3ms of advertised response time over my old Asus panel had planted preconceptions in my head. "Nah, it's not actually that bad, is it? I'll just keep using it."

Then it became super obvious when I booted up Far Cry 4. Yikes. It felt like garbage. I was using the exact same graphics settings as before, but the controls just felt so much worse. Vsync was turned on, and yeah, I understand that Vsync will always introduce an extra layer of lag in games. But on my older monitor it was still very playable. With my new monitor, not so much.

I decided to boot up an older, less intricate game (Counter Strike Source) just so I could mess around with Vsync and monitor settings, to get a feel for how bad the latency really was. I found that for the most part, playing any game with Vsync turned off was doable. Turning Vsync on, however, introduced just enough latency to push the overall lag into borderline unacceptable territory... which is unfortunate, because I like turning on Vsync in many of my games. Messing with the Overdrive settings on my monitor didn't do jack-squat. I tried changing the screen's preset to "game mode" to see if that would disable any kind of extra post-processing effect that would have been causing extra lag, but it made absolutely no difference.

I did some deeper research into this monitor. Tom's Hardware did an in-depth review of this model a couple years back, and while they speak overall positively of it, their analysis of "absolute input lag" (time that it takes from the signal entering the monitor to pixel change) looks pretty damning for gamers.



That's a whopping 52 milliseconds of total lag. And that's using a piece of hardware dedicated purely to testing lag, so it doesn't even take into account GPU, drivers, software, etc, etc.

We use a high-speed camera, shooting at 1,000 frames per second, to perform these tests. Analyzing video frame-by-frame allows us to observe the exact time it takes to go from a zero-percent signal to a 100% white field.

The pattern generator is placed at the base of the monitor so that our camera captures the precise moment that the monitor’s LED lights up, indicating a video signal being received by monitor. With this camera placement, we can easily see how long it takes to fully display s pattern after pressing the button on the generator’s remote. This testing methodology allows for accurate and repeatable results when comparing monitors.

That was when I realized that "pixel response" and "input lag" are two very different things, and good pixel response is almost worthless to me as a gamer when the monitor's internal electronics still take a whopping 50 milliseconds to actually register a signal. Even more frustrating, is that most (all?) monitor manufacturers are not keen on advertising this number whatsoever.

It also made me realize that some of the positive reviewers for the AOC I2757FH on Amazon sound delusional. 'No lag!' 'Great responsiveness!' (err, no.)

Suffice to say that I wanted to buy some better monitors... something with much lower input lag. (My other main criteria being that it's 27", 1080p, and IPS.)

During my journey I managed to stumble upon DisplayLag.com, a database dedicated soley to benchmarking the absolute input lag on hundreds of different monitors and TVs. The website was founded buy a guy who plays competitive fighting games where minimal latency is essential.

I narrowed down my options for new monitors and eventually came down to the HP Pavilion 27xi. It's 27 inches, IPS, 1080p, spectacular glossy screen, good reviews, and - according to displaylag.com - it has an "excellent" overall response time of only 10 milliseconds. I was skeptical of this measurement though. "How could there be that much of a disparity between similar spec'd monitors?" But according to displaylag.com, they use a method of measurement similar to Tom's Hardware. I figured, for only $200 the 27xi fits the bill, and if it's not an improvement then I can easily return it to Amazon. So I went ahead and and bought two of them.

The result? One of the best decisions I ever made. I love these monitors! Far Cry 4, Counter Strike, Vsync on, off, doesn't matter, all of my games play phenomenally. I was right to trust that display lag website. The input lag here on this monitor is MUCH better. Even though it's advertised as "7 MS (GTG)" response time - two more MS than the AOC model - that pixel response number doesn't even make a lick of difference to me. Pixel response time is higher but overall input lag is a fraction of the AOC model. I can see how this would mislead a whole lot of people.

Ultimately, I wish there were more indepth-reviews and analysis of monitors so I had a better idea of what I was buying. That displaylag.com website seems like a good resource, but it's not updated terribly often, and they don't exactly have every monitor in existence measured and posted. I sure do like the idea though and I may return to them again sometime in the future. For now, these Pavilion 27xi monitors have made me very satisfied.

I'm also now faced with the problem of having two extra IPS monitors that I'll never use, and I can't return them, so I'll have to figure out some way to sell them. D:

Thanks for listening to me ramble, and if anyone who's a noob like me learns something from this, then it was worth it.
 
Last edited:

sheh

Senior member
Jul 25, 2005
245
7
81
A site with detailed and technical reviews on monitors is TFT Central.
For TV input lag, other than DisplayLag, there's also HDTVtest.

Xbit Labs used to do elaborate pixel transition time testing, but not in recent years, and anyway now they're dormant.
 
Last edited:

Headfoot

Diamond Member
Feb 28, 2008
4,444
641
126
Long input lags a lot of the time point to a poor scaler/display controller that doesn't handle the IPS panel well. This is one of the main selling points of the Overlord monitor. Super low latency but still IPS.
 

Mondozei

Golden Member
Jul 7, 2013
1,043
41
86
Tom's Hardware has an unreliable method of measuring input lag.
They don't use dedicated hardware(oscilloscope), but websites like tftcentral and prad.de actually do.

For those that are interested in more.
 

SPBHM

Diamond Member
Sep 12, 2012
5,058
410
126
my HDTV from 2010 have a horrible input lag using the HDMI in (at 1080P), like even moving the mouse on windows ins painful, BUT using the analog VGA connection at 1080P the input lag is mostly gone, almost as good as my TN monitor... if I lower the res to 720P I noticed additional lag (but not as bad as HDMI at any res), so yes, I guess how the scaler works makes a huge difference.
 

kasakka

Senior member
Mar 16, 2013
334
1
81
Response time is important as well though. I went for about 5 years with a 30" 2560x1600 Dell and thought its response time and input lag (about 35ms) were just fine, didn't notice a difference compared to my Sony TV which according to HDTVTest was supposed to have a mere 10ms input lag.

Then I got myself an ASUS ROG Swift last year and the difference was marked. I was really surprised how much clearer the picture was in something really fast paced like Strike Vector. This is the difference between 8ms vs 1ms gray-to-gray response time - less blur.

I'm apparently not very sensitive to input lag apparently because I don't notice much of a difference between the ASUS and the Dell (about 4ms vs 35ms).
 

BFG10K

Lifer
Aug 14, 2000
22,709
2,980
126
Then I got myself an ASUS ROG Swift last year and the difference was marked. I was really surprised how much clearer the picture was in something really fast paced like Strike Vector. This is the difference between 8ms vs 1ms gray-to-gray response time - less blur.
No, that wasn't the response time, it was the 144Hz refresh rate.

In general the response time becomes meaningless once it's lower than the display's refresh cycle, which is 16ms for 60Hz displays. The only way forward at that point is either a higher refresh rate and/or a strobed backlight.
 

kasakka

Senior member
Mar 16, 2013
334
1
81
No, that wasn't the response time, it was the 144Hz refresh rate.

In general the response time becomes meaningless once it's lower than the display's refresh cycle, which is 16ms for 60Hz displays. The only way forward at that point is either a higher refresh rate and/or a strobed backlight.

You are right, I completely forgot about that since I'm so used to running at 120 or 144 Hz right now.
 

cmdrdredd

Lifer
Dec 12, 2001
27,052
357
126
Question related to this. Does GSync/FreeSync/Adaptive Sync change the response time or help with input lag vs just regular vsync?
 

Black Octagon

Golden Member
Dec 10, 2012
1,410
2
81
Question related to this. Does GSync/FreeSync/Adaptive Sync change the response time or help with input lag vs just regular vsync?

It helps with vsync-related input lag, yes, but it does not have any effect (AFAIK) on the response time. It also does nothing about input lag whose source is things like resolution scalers, OSDs, multi-input support, etc. The Swift is very good in the input lag department, and I daresay it's a result of having both G-Sync and being DisplayPort only
 

Omar F1

Senior member
Sep 29, 2009
491
8
76
Thanks for sharing.

Purchasing a new 27" IPS monitor definitely was a daunting and time consuming subject. Beside Prad.de, I remember reading long threads over HardOCP forums.
 

UaVaj

Golden Member
Nov 16, 2012
1,546
0
76
bump for excellent info.


yep.
live and learn.
for fps gaming. anything more than 16ms is a compromise.
for other gaming. anything more than 32ms is a compromise.
more than 32ms. do not buy. unless you are on igpu and clearly not gaming.
 

Bubbleawsome

Diamond Member
Apr 14, 2013
4,833
1,204
146
I'll take those IPSs off your hands for lets say... $20?

Seriously though, that is a great point, and the monitor you got fits what I am looking for quite well. Glossy, IPS screen with minimal lag.
 

MrK6

Diamond Member
Aug 9, 2004
4,458
4
81
Great points. One of the reasons I'm still on my old Dell 3007WFP-HC is input lag. Even though it's an older IPS panel and probably a bit slower than what's out there now, the lack of an onboard processor significantly reduces input lag and makes an awesome, well-rounded monitor for gaming or photo work.
 
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