120Hz and framerate

[Filiprino]

I can set my current monitor to a lower resolution and set it to 75, or 80hz. Even when I play a game at those refresh rates, as soon as my fps drops below the refresh-rate, I 'feel' input lag.

What you may feel is flicker, something really annoying on CRT screens.

The truth is that you don't need to maintain your framerate at the same speed as the screen refresh rate. That's hilarious.

Monitors are just DACs analyzing input. If they do not see new signal, they just keep displaying the same pixels. If something new arrives, they send it to the transistor matrix and starts to be displayed, row by row. That's why you see tearing with frame rates over the refresh rate unless you turn on V-Sync, because instead of launching new frames when you have them, refreshing pixel rows every X Hz from top to down, you send new frames when the whole pixel matrix has been drawn so the screen starts drawing a new frame when the last row of pixels has been refreshed (a full pass), i.e. you give enough time to get all the pixel rows properly refreshed without information from more than one frame if you can send new frames quicker than the screen can make full drawings.

 

[Meeho]

Right ok, I'm going to try and explain this as simple as I can.

lets say my screen refreshes at 60hz. And I'm playing a game, Lets say Call of Duty. (cos most people can run it). Now any fps over 60hz will run fine, because it is higher than the refresh rate. However when your fps dips below your refresh rate, you will experience some type of motion lag. You may not notice it at 59fps, but the further you go down the scale the worse it will get. Why? Because the game is producing frames that are slower than the screen. You will eventually get to the point where you can 'see' this happening. So you move your mouse and then the game moves half a second later.

That makes no sense. Why would you get more lag because you monitor is capable of showing more frames than it is getting?

At 60hz, there is a difference of 16ms between each frame. Between each frame the game has to 'read' what inputs the user is creating. (eg mouse and keyboard). Now the lower the fps we go the longer between these frames. This means that the game is reading the changes of your 'mouse' at a 16ms rate. When your fps drops, the frame width gets larger. this means that per second your mouse is going to be read less times. This will mean the mouse will feel less accurate, because the intervals in which it's being read further apart.

The mouse doesn't have to be read in longer intervals, but the results will take longer to display at lower FPS.

Now lets take the issue at hand. Your running a 120hz screen. So in order for the game to keep up with the screen, you need to run the game at 120fps or more. This is easy to do in game like cod.

set your fps to 125fps. Why 125, because it creates a 'whole number' of ms between each frame.

60fps 16ms/frame
91fps 11ms/frame
125fps 8ms/frame
etc...

There is no need "for the game to keep up with the screen".

So /com_maxfps 125 [to set the fps cap at 125]. and /cg_drawfps 1 [to see the fps counter]

You will find that game play should feel fine at 125fps, but as soon as it dips under 120fps, because you screen is 120hz, you will start to feel the lag.

So, i know you have this fancy 120hz screen, but you maybe better off playing with a lower refresh rate while playing BF3. So that your fps, doesn't dip below your refresh rate.

What you're describing is the specifics of the COD/Quake engine and its sweetspots at 125, 250, 333 FPS...but it has nothing to do with the display refresh rate.

I understand that I am a 'noobie' on the forums, but I have spent may years of online gaming understand these effects and getting the best performance out my games.

I think you're correlating independent things. There is no reason for a 120 Hz display to show more lag at, say, 50 FPS, than a 60 Hz display.

 

[Inu]

Do you have a normal 60hz monitor for comparison?

 

[striker444]

I found an interesting article that should clear up a lot of confusion here

http://www.anandtech.com/show/5728/...ew-asrock-asus-gigabyte-msi-ecs-and-biostar/2

Apparently LucidLogix is going to fix some of the issues discussed in this thread not only with 120hz monitors but 60 hz and vsync

"Lucid’s goal is to improve the 'immersive experience' by removing redundant rendering tasks, making the GPU synchronize with the refresh rate of the connected display and reduce input lag."

 

[Simkin]

The conclusion here is that there is nothing wrong..

120Hz is not supposed to work any good in 60Hz mode, either does it suppose to be working smooth @ 60fps in 120Hz mode either.. Why someone is saying this, i dont know, but it clearly is BS..

If someone is saying 60FPS is smooth on their 120Hz, then they have very low requirements to smoothnes.

So, everything is cleared up here =)

 

[Tup3x]

I found an interesting article that should clear up a lot of confusion here

http://www.anandtech.com/show/5728/...ew-asrock-asus-gigabyte-msi-ecs-and-biostar/2

Apparently LucidLogix is going to fix some of the issues discussed in this thread not only with 120hz monitors but 60 hz and vsync

"Lucid’s goal is to improve the 'immersive experience' by removing redundant rendering tasks, making the GPU synchronize with the refresh rate of the connected display and reduce input lag."

That's indeed interesting. I'll definitely try it out if my next motherboard supports it.