SLI not smooth below 60 frames per second

[mof]

I've only tried a few games with SLI and I've noticed that when using SLI, in order to make it feel smooth, you need a much higher frame rate than you would need with just one card.

E.g 1. The division with one card running at roughly 30 FPS felt fine to play.
With SLI running in the 40s FPS (also not scaling very well) it felt really stuttery and wasn't really playable. It wasn't until I'd reduced the settings enough to get a constant 60 FPS that it felt smooth to play.

2. The Witcher 3: With SLI getting 50 FPS it doesn't feel good at all. Yet as soon as I get the settings down a bit and it's running at 60 FPS constantly it's playing completely smooth and flawless.

Normally with 1 GPU I can play at 30-45 FPS and not have any problem whereas with multiple GPUs anything below 60 feels crap.

I was playing the Witcher with the frame limit set to 60 (60 Hz monitor) and adaptive v-sync on. I tried turning v-sync completely off but I still got the same result.

Using "smooth v-sync" in the nvidia control panel does help with this but it lowers the frame rate so much that you might as well be on one card.


Is this something that other people find with multi GPU set-ups?
Does it happen with higher refesh rate montiors?
If so then I'm glad I only have a 60Hz one.

 

[mof]

Depends what gpus you have I suppose? I'm lucky that mine just don't drop so low for me to notice, but I'd be disappointed to have sli and only be getting 40 fps in the Division.

Yeh it is disappointing. Although that was @4k with everything turned up. I can change a few settings to get a constant 60. The division seems to have poor scaling despite the high usage on both gpus.

Crysis 3 has great scaling. I haven't tried either of the tomb raiders yet but apparently they scale well too.

 

[mof]

Anything below about 50 fps with 1 gpu feels crap unless you have gsync/freesync. Are you sure 1 gpu at 30-45fps is as good as you remember?

I'll have to try it out. I'm not saying it's perfect but just playable.
The witcher 3 @ 50 felt terrible - more like 15 frames. Didn't look right either it was kind of like tearing but different. It might have been micro stuttering like Meaker said. The frame rate was constantly jumping from 50 to 51 and back again. With smooth v-sync on this didn't happen. It was a constant 30 fps.

I ended up going back to using 1 card for the division.

 

[mof]

I think it must've been micro stutter. Starting to notice it even when fraps is showing a constant 60 fps (on the Witcher 3).

 

[mof]

I always found SLI stuttery under 60 fps when in fullscreen windowed mode, in pure fullscreen mode it was fine. Especially in witcher 3.

Thanks. I'll make sure it's fullscreen mode. I thought you couldn't use sli in windowed mode but that must be just crossfire.


Also I think I have a bit of a problem with adaptive v-sync in general. It doesn't get rid of tearing completely or I'm seeing something similar to screen tearing that goes away completely with full v-sync on. I think my monitor (philips bdm4065uc) might be more prone to this kind of thing more than others. Probably not an ideal gaming monitor but I use it for tv/films/wiiu/general pc use aswell.

I'm going to try full v-sync with SLI and see if that helps the performance.

 

[mof]

Adaptive v-sync will apply regular v-sync when your GPU is outputting 60FPS+ (or whatever your refresh rate is). If the frames dip below the refresh rate, v-sync gets disabled which will result in tearing again.

It's meant for people who want to prioritise frame rate over tearing, the benefit being it doesn't drop to half your refresh rate like normal v-sync.

Yeh that's what I thought it was. Somewhere inbetween v-sync on and off.

I always thought I was getting tearing when the frame rate was below the screens refresh rate but then I heard it only happens when it's above the refresh rate.

So you can still get tearing with adaptive v-sync on when the frame rate is below your screens refresh rate?

 

[mof]

OP, have you tried locking the frame rate at value which your cards can hold constantly or even don't drop under if it's high enough? You can do it via MSI AB per game (create a profile) and it was a "fix" i used for some games that had bad frame times - back then no one was really talking about this. AMD has a similar option for profiles in the drivers, nVIDIA may have (not sure) as well - in case you dislike Afterburner.

I'll give that a go. I imagine it has similar results to using smooth v-sync - smoother steady but with lower frame rate.

EDIT: The Division SLI scaling seems to be better now. I'm getting around 60 frames in the benchmark when I was getting 40. The problem is the game crashes now.