The science behind why resolution affects frame rate

[thorpj]

Yes, a higher resolution means that the GPU has to render an image with more pixels, so it puts more of a strain on the GPU, and the frame rate is lower. I get that

 

But i'm looking for a scientific explanation, or at least, something more in depth than that. I can't find any information about this anywhere, but i'm hoping that the LTT forum can help!

 

thanks

[Blackwash]

Each time the GPU renders a frame, it sends the information to the monitor, which then fills up each and every pixel with the specific information sent by the GPU.

Think of it like an RGB matrix, with each color above the main three having a specific color code.

High quality "pictures" need quite more information to be sent from the GPU and delivered to the monitor.

 

The more you ramp up graphical settings, the more information the GPU has to collect and send out to your display.

One of the biggest hog is of course resolution.

 

Typically, when you set your resolution, your GPU knows how many pixels it works with and has to sent data for.

 

The more pixels on screen, the more information the GPU has to output.

 

Of course, before it is able to send it via the video signal, it needs to collect data and render a frame.

 

Now, as we all know, a "video" is nothing but a series of fast moving pictures in front of our eyes.

 

The video card takes into account the amount of information it needs to send out to the monitor, the amount of pixels it needs to fill up.

 

Then (if the frame rate is unlocked) it starts sending out the needed signal towards the monitor, at the maximum possible speed it can.

 

The more "demanding" a game is, the more it requires the GPU to do before sending out a complete frame.

 

The reason behind why frame rate dips when you ramp up the resolution, is because the video card needs more time to process a frame.

 

That is where the good old "frame times" come in, which measure not the frame rate, but how much time currently is needed by the GPU to render a single frame.

 

Typically, for 60 frames per second, the frame times are around 16.7 ms per frame.

 

The bigger the frame times, the more TIME consuming is for the GPU to render a single frame.

 

The more time it takes for the GPU to render a single frame, the more TIME it will obviously take to fill up a second with a given number of frames.

 

P.S. - Not really a scientific way of explaining it, but a tad more in depth I suppose.

 

Hope this kind of helps.

[thorpj]

-snip-

That is exactly what i was looking for, thank you!

 

Scientific was probably a poor choice of words on my part

[Blackwash]

Glad I could be of some use then.  :lol:

 

Cheers.

[thorpj]

Glad I could be of some use then.  :lol:

 

Cheers.

Cheers

[MMKing]

The effects of increasing resolution can differ wildly from game to game, and to a lesser extent from gpu to gpu. Using the witcher 3, 2560x1440p vs 4k and the 980 as an example.

 

http://www.guru3d.com/articles_pages/the_witcher_3_graphics_performance_review,6.html

 

980 2560x1440 = 48 FPS

980 3840x2160 = 28 FPS or 58.3% compared to 1440p

 

The amount of pixels however, is 225% compared to 1440p

 

This is because, even though there are more pixels to render at 4k. The act of calculating reflections, shadows and physics don't change very much or at all changing from one resolution to another, given the same settings.

[thorpj]

The effects of increasing resolution can differ wildly from game to game, and to a lesser extent from gpu to gpu. Using the witcher 3, 2560x1440p vs 4k and the 980 as an example.

 

http://www.guru3d.com/articles_pages/the_witcher_3_graphics_performance_review,6.html

 

980 2560x1440 = 48 FPS

980 3840x2160 = 28 FPS or 58.3% compared to 1440p

 

The amount of pixels however, is 225% compared to 1440p

 

This is because, even though there are more pixels to render at 4k. The act of calculating reflections, shadows and physics don't change very much or at all changing from one resolution to another, given the same settings.

That's good to know, thank you