I’ve got a tick running the rotation of the directional light source in a level, and for some reason it just stops randomly working with Nvidia video cards. I’m using 4.2.1 if it matters. anyone else had a problem with this?
How do you know it’s just with Nvidia graphics cards?
I guess I don’t Know for sure, I have two Pc’s in my office, one amd and one nvidia, and for some reason this only happens on the NVidia pc.
I’m not sure, that nvidia causes this problem. Maybe there is another problem with ur code, that lags on that “Nvidia” PC. I had such problem, but that was because of complex logic that was running every tick.
Btw, what nvidia card do u use?
I’m not sure what card it is, I think a newer GTX. Did you Ever find a workaround?
So I found a bit of a workaround, By increasing the the multiplier.
pretty vague question w/o knowing what you are actually doing, no one here can answer correctly.
some problems may occur with your light (lighting) for one thing
another is if you are overusing Tick nodes
you could post the code or a pic of the BP to show what you are actually doing or trying to do, this always helps
also sometimes Answer Hub is better for certain problems
good luck tho’
also almost all NVidia cards (that I know of), if you right click on your desktop screen & hit NVidia Control Panel then Help then System Information should show what video card you are running. 
but also this could be a processor problem if you have any that are about to break etc. again here just right click on computer in your start menu & then properties should show what processor you are running