How does input lag for monitors (and peripherals) make such an important difference?

I was discussing this on a thread about the Wasabi Mango and I started wondering about this.

How would this stuff make a win or lose difference in a game? I'd think the human reaction time is vastly slower. If you had the information instantly in parallel with the screen I think the screen would reproduce it visually faster than you could process it and react, but then again if you have to wait for the monitor to reproduce it before you start reacting, that would sensibly be not ideal. Still, like, these differences don't seem to me to be such as to make a difference in who sees who first and who shoots first. Especially compared to sending said reactions over WAN to the server to process; that seemingly would make a much bigger difference and filter out all these piddly little time differences (monitor input lag and also peripherals) by comparison.

This isn't a challenge or criticism, I'm honestly curious. What's the deal?

Unless you play CS:GO/Quake/Unreal it really doesn't matter, it's just that you want to try and shave off as much delay as you can given how fast those games can move, CS:GO less so than the others

Basically the sooner you can see something the sooner you can react to it, my main display is now a CRT running at 85hz, though I gotta get me a higher end CRT someday

CS:GO AWPing mid on dust2 the difference in refresh rate makes a big difference.

If you're running 144 and still have a 30ms lag that might be the difference in that shot at the doors depending on the tps of the server.

It makes a big difference for ~1% of all players...I.E. the pro level players. Your average Joe CS:GO player doesn't have the skill level to react any faster even if given an extra frame.

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I also consider myself a game tourist, I like looking at the digital worlds (when possible without being disturbed); I wish there were a tourist mode !
For me, in all uses I could not find a situation that the 2 to 3 frames behind hindered me; usually at that point i am already dead :-(
However, the crispness of the display and the fluidity of my movements or reactions is, to me, instantaneous ! So the speed of the A399U, the A409U and the crossover 404K are quite adequate for the average to difficult joe. (IMO)
edit 1 = as you, i often wonder what the whole fuss is about ! (to a certain degree yes, but always ????)

I personally think, even though a human's reaction is relatively slow to a computers over a vast network it still matters if someone is a fraction faster than the other. For example; lets say a PC's ping to a server is 60ms, than the other persons is the same.. so it will take 120ms to confirm a movement or shot for the server and you. Now if they other guy had a CRT and a PS2 mouse and keyboard he'll only have added about 10ms on each moving overall lag to 140ms, but you have a USB wireless mouse and monitor with signal processing that add about 60ms on each making a total of 240ms.

To give you perspective there is a noticeable difference with a 20-40ms change in something BUT! only 1ms to win an exchange on a server.

There other aspects that lower lag as well, like refresh rate. That increases the polling rate other than making it look more solid lowering the time the image gets to you. That's why they also advertise polling rate on mice too. So a 144hz monitor will be better than a 120hz monitor if you plan on something competitive despite that once you pass 100hz its hard to tell, and from 120hz to 144hz is VERY hard to notice.

I would also only really care if its a twitch shooter, strategy or more casual games don't matter as long its working lol.

It does not. May be there are some people, bit this is so blown out of proportions... Even more so than PhysX... And it is even more pointless if you ask me... But that is just me...

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All I can say is when I used to play Halo I could INSTANTLY tell if a monitor/tv had bad input lag. It literally made the games unplayable. Cut my skill in half. I played on a CRT till 2014 just because of the absolutely minimal input lag.

Granted, some of the TV's back in 07 had input lag of like 60ms+ so those I am sure most people could feel. Now as for people claiming 10ms input lag or whatnot affects their gameplay, I couldn't say anything on that matter. I would think it is like you said in the OP, other factors matter much more.

I got a slow Dell u2711 and honestly I don't notice that stuff. Then again I'm not a pro gamer. Not even an enthusiast. But mathematically speaking you do still get some extra time to react to your surroundings.
Let's say you have an input lag of 30 ms. If someone walks around a corner and your GPU sends the image to your monitor but it lags behind the signal for 30 ms, so whatever happened already happenend 30 ms ago, you just couldn't see it yet.
Let's say you can process and react within another 100 ms (Which probably isn't true, but just to give a number)
So it's 30 + 100 = 130
That's 130 ms delay between the time when the enemy is visible and your final reaction.
If you have a 5 ms monitor lag then again it's:
5 + 100 = 105
That means it's only 105 ms until you start firing. Basically your brains information processing can start 25 ms earlier.

I'm in agreement with what seems to be the consensus here: that it's not a big deal for most gamers in most games.

The best way to see what kind of difference it will make to you in the games you play would be to test it out for yourself. You can create an extreme input lag scenario for yourself by running Steam in-home streaming over a wireless network and using wireless inputs. This would give you an absolute worst-case experience, worse than just about any new monitor you could buy using a direct connection.

I actually find Steam IHS over wifi adequate for slow-paced games, and could probably get used to it for even fast-paced single-player games. Twitch multiplayer games, however, would be pretty much out of the question for me.

Them frames
I'd say that If you can see it, its already problem no matter if you can react to it. For me this stuff just comes as clarity, and when it gets worse I dont even get whats going on.

Then when it comes to these mysterious Pro gamers, I've seen from YouTube clip some CS:GO player quick scoping so fast that I couldnt see that "headshot" frame, and just saw the scope moving and animation to unscope while the enemy is dropping.
This kinda made me realize how amazingly fast some people can be, and I just ..amazed yeah. WTF?

But if you can be Pro or not shouldnt make any difference, this is just about your eyes. Not about reflexes, skill, or if you can notice it without someone showing it for you.

Yesterday Sapphire Ed were rambling something about resolution and "superhumans", and although I think he meant about the issue where people force their view on others? as he asked us to kindly shut up. :D
It reminded me from pixel topic whats as mystery as frames, refresh rate, and this delay.

For me:
23" 1080p is full of black squares
27" 1440p is pixels without those black borders, and I start seeing those borders again when 40cm~ away

and I'm sure there are people who see 27" 1440p as black squares just by relaxing there, not to mention that this black gets mixed with colors.