Horizons Strange Vsync problem

[ClaudiuC]

Hi, I have a strange vsync issue with Horizonts, I have quite a beefy system:

Core i5 6600K 4.3Ghz OC
MSI GTX 980 Gaming OC
2x4 Ghz DDR4 3000 Mhz
Win10

Now I am playing Horizonts with everything maxed out on 1080p and I usually get between 120fps-280fps ... now from time to time I get some screen tearing so I tough ... alright, since I get such a good performance anyway I can just enable vsync and limit my fps to 60 and also fix the screen tearing isssue but now comes the strange part: with vsyn on I usually get 60fps but there are situation where I get some fps drops as low as mid 40:
-during supercruise(specially when entering or exit)
-sometimes during fighting or near space station

So I am puzzled, since the game runs so well on my system(never drops bellow 120fps anywhere) why do I have this fps drops with vsycn ON?
Also I've never seen this behavior in other games where vsync will just cap the fps to 60 usually.

Any suggestion is welcomed!

 

[Ravenov]

I had something similar, it would be either 60fps or 30, with no in between. I turned v-sync to adaptive in the nvidia control panel, and i think i may have turned it off in game, but put the fps limiter on at 60hz instead ... something fixed it because i haven't had the problem since.

 

[Dannyc]

Not 100% sure but I think it's to do with how the hz is divided to the next possible sync even though you may only have lost 1frame. When your running with it off you won't notice. But when its on it can't just drop 1 it has to drop to the next allowed sync and as the difference is more substantial it shows as a stutter

 

[ClaudiuC]

Not 100% sure but I think it's to do with how the hz is divided to the next possible sync even though you may only have lost 1frame. When your running with it off you won't notice. But when its on it can't just drop 1 it has to drop to the next allowed sync and as the difference is more substantial it shows as a stutter

That might be a plausible explanation, thanks!