on the PC, if your FPS is higher than the monitor's refresh rate, you only get the refresh rate as the number of images presented to the player per second - right?
so if i'm at 172 fps (pulling a number out of thin air), and the monitor is at 60Hz, the player sees 60 images per sec - right?
Well, yes and no.
The screen will only do a redraw every 1/60 of a second, but the player might well see some of three frames of data as the source data gets updated while the drawing is happening - and it'll be a torn mess.
so there's really no need to go faster than refresh rate? you're writing data to vidram that never gets sent to the monitor? overwritten before it ever gets read?
Not if you want a clean image, no.
The data will get sent to the monitor however, you'll just see artefacts in the image.
Example; monitor is drawing at one new frame every 16ms but you are presenting new data every 8ms, then half way down the screen the new frame of data will be presented which will likely be noticeable.
(Things won't get 'over written' at the GPU stage because you'll be presenting a different back buffer each time)
and refresh rates are typically some multiple of 30 Hz ?
No.
Some monitors can run at 72hz, others at 144hz for example; others such as Freesync or G-sync monitors have no fixed update rate and will refresh on demand.
I'm running caveman 3.0 on the new i7-6700K at 4Ghz and a GTX1080. with framerate limiter off, i show 62 fps. due to vsync no doubt.
Do not assume; profile.
Check what the profilers says you are doing both CPU and GPU wise.
Never guess.
Always use tools.
And if your frame rate limiter is off then you'd see 60fps if you were v-sync locked with a monitor which can do a max refresh.
If you have vsync off as well and only seeing 62fps then the limit isn't vsync.
game is currently coded for 15Hz update, so i'd have to mod all update code to run at a different speed. such as 30Hz or 60Hz. (or 120Hz ?)
This is why games decouple their updates so that everything can run at different speeds and adapt to the system they are on aka part of the reason why Fix Your Time Step is such widely given advice.
The games which don't do that tend to be console titles, where they tune to the hardware and then limit the PC version in some manner; such as games which update at 30hz and rely on v-sync to keep things in check... and then go wrong when v-sync is disabled.