FreeSync 30hz Question

[BlackGuyRX]

I've noticed with a lot of FreeSync ranges, they don't seem to dip below 40/48hz on average. Same with any G-Sync compatible display. I bring this up because as a Mame fan, there are some games I play that run in 30hz, mostly some old Midway games like Rampage, Tapper and Satan's Hollow. Also some Intellivision games which apparently run at 20hz. Is there anyway to get 30hz out of these displays or am I limited to native G-Sync monitors? I do prefer those but ones with the modules seem to either be going way of the dodo or are only used in more expensive units like the ultrawide & larger 4K displays. I really love the idea of G-Sync compatible being a thing but my GTX 970 card isn't compatible and I don't like how none of them appear to go below 40hz.

Is there any way to get 20 or 30hz out of those monitors and still have VRR? Is it a limitation spring from the hardware or specification?

[RealNC]

I think you're confusing FPS with Hz. It seems highly unlikely that any CRT displays would run at 20Hz or 30Hz.

[Chief Blur Buster]

Short answer:
20fps on a FreeSync or G-SYNC monitor will usually cause it to run at 20fps@60Hz autotmatically using automatic Low Frame Rate Compensation (LFC). LFC can be superior to non-LFC for well framepaced software like high quality emulators or anything outputting consistent frame times. LFC erratic-stutter only happens when the game is outputting erratic frame times.

LCDs have decay issues for long duration refreshes, so more repeat-refreshes can help as long as they don't interfere with stutter (LFC will succeed in prevent collisions between repeat-refreshes and game-presents if frametimes are non-erratic). The important thing is that you have to have LFC, then your consistent (non-erratic) low framerates are as good as native Hz.

I have a longer technical answer for those interested...