Question about Freesync and FPS

[Netherspark]

I'm completely new to Freesync, and while there's plenty of information about what it does I still have a probably stupid question:

My understanding is that it essentially works like V-Sync in reverse - it scales the refresh rate down to match the frame rate instead of the other way around. So if I have a 144hz Freesync monitor, and my game is running at say, 90 FPS, what happens? Does the refresh rate of the monitor scale down dynamically to 90hz?

 

[sizzling]

Yes it will be 90Hz but its doing more than that. The frames from the gpu and the monitor refresh at the same time. With v-sync the frame refreshes on the gpu and is held for 1/60 second (assuming 60 Hz), at any time while the gpu is holding the frame the monitor will refresh so the image you see can be slightly delayed up to 1/60 of a second.

This is how you get smoother pictures and less lag while using freesync/G-Sync even at lower fps.

 

[Netherspark]

I see quite a few people saying that it doesn't work very well, that it would struggle to cope with a difference of more than a few hertz, or causes screen flickering. Is there any basis in these claims?

 

[Gaidax]

Well I am coming from the evil corporate GSYNC standpoint and it seems to work as advertised, I'm pretty sure Freesync is in the same boat and even if there are issues there is probably more good than bad to it, otherwise you'd sure hear A LOT of negativity about it, instead of some random rare thing here and there.

Worst case you can surely turn it off, the thing is piratically free anyway.

 

[Netherspark]

So there shouldn't be any problem in Freesync scaling 144hz down to such a low level as 90hz?

I just keep seeing people saying "it won't help that much".

 

[sizzling]

I'm not aware of any issues with GSYNC but Freesync is supposed to be very slightly behind GSYNC but much cheaper. Both are better than a standard monitor for gaming, normal monitors have their own problems.

 

[Gaidax]

So there shouldn't be any problem in Freesync scaling 144hz down to such a low level as 90hz?

I just keep seeing people saying "it won't help that much".

There is a nice example of what is it like without GSYNC (and Freesync) and with.

Without GSYNC/Freesync: https://www.testufo.com/#test=stutter&demo=tearing
With GSYNC/Freesync: https://www.testufo.com/#test=stutter&demo=gsync

VSYNC can also give like above, but then it has another issue - when your FPS is lower than 60 it may introduce:
With VSYNC at low FPS: https://www.testufo.com/#test=stutter&demo=stuttering

Freesync is a bit worse in that it does not work below 40 FPS/Hz, but other than that it's pretty much about the same as GSYNC and certainly can help as you see above.

Tearing is noticeable when your FPS is above 60 and is annoying at times, the above demos are worst case scenarios, but you will see that happen ingame too - basically the top part of the screen will be next frame and bottom will be previous frame, it's happening for split second, but it's noticeable.