What's the Relationship between FPS and Refresh Rate

[imported_phupper]

As I understand it, a high end video card won't give you high FPS unless your monitor also supports high refresh rates. Is this true? What is the relationship, if any, between Windows Monitor Refresh Rate, and FPS in games like Q3A?

Thanks,

phupper

 

[ribbon13]

If your monitor is at 60Hz (icky!) it won't display more than 60FPS
If your monitor is at 85Hz it won't display more than 85FPS

The focused eye can't distinguish more than ~35FPS, and roughly twice that peripherally. So the real goal is to have a minimum framerate that never falls below 70FPS for smooth gameplay.

 

[Sunbird]

What he said. You don't want your minimum frames per second (say from a scene with lots of action) to drop lower than the refresh rate.

 

[SVT Cobra]

exactly what you said is true ribbon, good explanations,

also though there have been tests(looking for a link to back it up) that the hir the frame rates, even over 100, the quicker a human mind can react and anticipate, so while the human eye (the consious part of your brain cannot distuingush any more than 35ms, the subconsious mind can, which when in the "zone" can make for awesome reaction times, hence to extreme drinking og caffiene at Lan Parties to increase that outta there feeling....


yeah CS is way to competitive lol

 

[Suspicious-Teach8788]

Yes, so thus I need high quality graphics because my high quality monitor does 100 Hz default (120 max) at 1024x768 and 87 for 1280x1024. ehehe

 

[imported_phupper]

"If your monitor is at 60Hz (icky!) it won't display more than 60FPS"
"If your monitor is at 85Hz it won't display more than 85FPS"

That can't be right. My monitor maxes out at 120Hz (recommended for my Radeon 9800 Pro), 200Hz if I push it. But in Q3A I get 250 fps.

So it's still a mystery...

 

[SynthDude2001]

Originally posted by: phupper
"If your monitor is at 60Hz (icky!) it won't display more than 60FPS"
"If your monitor is at 85Hz it won't display more than 85FPS"

That can't be right. My monitor maxes out at 120Hz (recommended for my Radeon 9800 Pro), 200Hz if I push it. But in Q3A I get 250 fps.

So it's still a mystery...

Your video card can draw 250 individual frames per second in Quake 3, but the monitor cannot display that many. The most frames per second you'll actually see is the number of times per second your monitor can refresh.

 

[Concillian]

Originally posted by: phupper
"If your monitor is at 60Hz (icky!) it won't display more than 60FPS"
"If your monitor is at 85Hz it won't display more than 85FPS"

That can't be right. My monitor maxes out at 120Hz (recommended for my Radeon 9800 Pro), 200Hz if I push it. But in Q3A I get 250 fps.

So it's still a mystery...

You can measure 250 FPS, but your monitor isn't actually displaying 250 FPS.

apps that measure FPS ignore what the monitor is displaying unless VSYNC is ON.

 

[FuZoRBlade]

1 fps = 1hz

but thats just the maximum refresh rate, it doesnt always display that refreshrate.

 

[corkyg]

OK - is there a relationship that goes with the type of monitor, i.e., CRT vs LCD? LCDs do not have "refresh rates." They are staring pixels. Just curious.

FPS

 

[Concillian]

LCDs are more difficult. They do not have refresh rates, but they do have response time, which is similar.

For example, a response time of 16 ms = 1/.016 = 62.5 possible color changes per second. It's not exactly the same, as response time is different for different color changes (generally shorter for black to white, longer for transitions between closer colors). What is generally advertised is the response from black to white, which is usually the shortest transition.

The 8ms panels that exist are a max 125 Hz, and usually less than that. Basically you end up in a similar place as CRTs around 70-100 or so.

 

[Mark R]

LCDs do have refresh rates but they work slightly differently to CRTs.

On a CRT, only one 'pixel' is illuminated at one time - the electron beam is swept across the screen left-to-right, row-by-row. The pixel illuminated corresponds to the signal being send from the computer at that precise time, and the brightness and colour of that pixel depends on that signal.

A refresh rate of 60 Hz, means that the beam makes 60 sweeps of the whole screen per second. The eye has a slow response time (equivalent to about 30 Hz), so it blurs out this sharp flickering - but nevertheless a high refresh rate is needed to reduce the flicker so that it is not actually noticable (about 85 - 100 Hz).

On an LCD, every pixel remains illuminated continuously - there is no flicker. However, the information is still being pumped pixel by pixel from the PC. When a pixel receives a signal that is different from what it is currently displaying - it starts changing colour. This process of changing colour takes some time. This is the LCD response time.

So, if your LCD is running at a refresh rate of 60Hz - it will receive a set of instructions every 1/60th of a second. However, if the response time were 25 ms, then it would mean that a colour change instruction would take 1/40 of a second to complete.

 

[corkyg]

Originally posted by: Mark R
LCDs do have refresh rates but they work slightly differently to CRTs.

On a CRT, only one 'pixel' is illuminated at one time - the electron beam is swept across the screen left-to-right, row-by-row. The pixel illuminated corresponds to the signal being send from the computer at that precise time, and the brightness and colour of that pixel depends on that signal.

A refresh rate of 60 Hz, means that the beam makes 60 sweeps of the whole screen per second. The eye has a slow response time (equivalent to about 30 Hz), so it blurs out this sharp flickering - but nevertheless a high refresh rate is needed to reduce the flicker so that it is not actually noticable (about 85 - 100 Hz).

On an LCD, every pixel remains illuminated continuously - there is no flicker. However, the information is still being pumped pixel by pixel from the PC. When a pixel receives a signal that is different from what it is currently displaying - it starts changing colour. This process of changing colour takes some time. This is the LCD response time.

So, if your LCD is running at a refresh rate of 60Hz - it will receive a set of instructions every 1/60th of a second. However, if the response time were 25 ms, then it would mean that a colour change instruction would take 1/40 of a second to complete.

Refresh rate and response times are not the same. As you said, LCD pixels are constantly being illuminated - that is what "staring" means to an electro-optical engineer.

Further - you can change the video card's refresh rate for an LCD and it will have no visible effect on the displayed image.

The correlation between response time and refresh rate you make is as it relates to the human eye's perception of it. Technically, they are not the same at all.

 

[BenSkywalker]

The focused eye can't distinguish more than ~35FPS

Just like to point out that that is laughably inaccurate. Anyone can download fpscompare if they can find it online and see for themselves. It is very easy to tell the difference between 70FPS and 100FPS focused- even for average people.

 

[Concillian]

Originally posted by: corkyg

The correlation between response time and refresh rate you make is as it relates to the human eye's perception of it. Technically, they are not the same at all.

But still response time is related.

You can maintain 200 visible FPS if the color doesn't change, but does FPS really matter then?

There is a pre-supposition that the image is changing when we talk about FPS. In this case the color of the pixels must also change. There is no crisp defined relationship of FPS to refresh rate as there is with CRTs, but there is still a relationship of response time to FPS.

Eventually it boils down to a philosophical discussion as to whether a frame can be considered rendered if the pixel is still in the process of changing it's color. To some it will be, but to others it won't. For those who consider the frame rendered, there is no FPS limit on LCDs, for the others the limit will be somewhere between 0 and 1/response time.

 

[imported_phupper]

Wow, thanks for all the input on my original question. There is another aspect of refresh rates I think plays a roll. I don't know what it's called (something like persistance), but it's the time it takes for the pixel to go off, or change from white to black. It can be seen as the trail behind the white mouse pointer as it sweeps across a black screen. I'm not sure what determines how fast the pixels turn off, but wouldn't that have some limiting factor on the visual distinction between refresh rates?

 

[slightlyhuman]

here's my question:

i run 1600x1200 res in windows but 1024x768 in games. my monitor(not the best) runs at like 70hz at 1600x1200. but since i'm running a lower resolution in games(1024x768) will i get the refresh rate of 1024x768 or 1600x1200?

 

[kobymu]

Originally posted by: BenSkywalker

The focused eye can't distinguish more than ~35FPS

Just like to point out that that is laughably inaccurate. Anyone can download fpscompare if they can find it online and see for themselves. It is very easy to tell the difference between 70FPS and 100FPS focused- even for average people.

it is not as simple as that. there is a big difference in how the brain analys the visual input between still image and motion. most peple can distinguish up to 25 diffrent images pe second (ie a 1 minute video clip in which every frame is a complatly difference from one another), however in motion the brain does not process all the visual information that it receive and it can go as high as ~150 "fps" in low complexity scenes (ie a video clip of black ball in motion on white backround, the brain will only process the information of the black ball and some of the white background, and more specifically the immedate white background aroud the black ball).
i read somewhere about an experiment that prove the above statment. and one of it's conclusion is that because "in the jungle" it is very impotent to notice movment for survival, our brain evolved in such a way that it specialise in distinguishing movment (as in opposed to distinguishing the differences between two different images), "it knows" what information to process and what information not to process.

/edit

and like all other homen capabilities it can differ from one to another to some extent.
ie the 25/150 cap limit is not absolute.

 

[kobymu]

Originally posted by: phupper
Wow, thanks for all the input on my original question. There is another aspect of refresh rates I think plays a roll. I don't know what it's called (something like persistance), but it's the time it takes for the pixel to go off, or change from white to black. It can be seen as the trail behind the white mouse pointer as it sweeps across a black screen. I'm not sure what determines how fast the pixels turn off, but wouldn't that have some limiting factor on the visual distinction between refresh rates?

that phenomenon is caused by you'r brain, not the monitor. it is some kind of photomontage (like the blure effect)

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