Originally Posted by JackCY
Limit of 73fps on a 75Hz monitors is of course going to spit out frames that are jumping over 75fps. The limit is often made that it adjusts the sleep time of next frame not of current frame (which would add other issues, stutter, improper timing really) based on previous frametime.
If you want to run near refresh limit with no tearing you need to use either fast/enhanced sync or Vsync.
People often think that if they set an FPS limit that no frame will go above it but that's not how it works.
Lets say fps (although normally this is all done in times = frame times not fps because computer gives you time and you can calculate fps from that if you want to):
limit 73, max 75Hz
2 74 above limit of 73 ==> sleep a little before calculating next frame
3 100 above limit of 73 ==> damn it sleep some more! again
4 65 below limit ==> don't sleep again
The frame times/fps can be all over the place, GPU do not have static fixed performance, they adjust their performance, the scene changes all the time, other loads on your PC, ...