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SLI Stuttering below 60fps

jc0

jc0

jc0

Associate
Joined
13 Jan 2013
Posts
185
Hi all,

This is a problem I've had ever since I purchased my PC a few years ago, and one that I've never been able to fix so thought I'd ask here!

I have an i5-3570 system with 2 x EVGA GTX 670 4GB FTW cards in SLI, 16GB RAM.

I always have v-sync turned on in all games that I play otherwise I get terrible tearing. I get a silky-smooth gaming experience when I'm playing, unless the fs drops below 60fps and then it becomes stuttery/jerky. I don't know if micro-stuttering is the correct term because 'micro' insinuates it's difficult to detect but this issue is very obvious. Even at 56-57fps the issue is very noticeable then as soon as it goes back up to 60fps...smooth as silk again.

I don't use adaptive v-sync, but trying it didn't fix the problem. This issue occurs with all games that I've played, it isn't specific to one game, although at the moment I'm mostly playing FC4 and AC Unity. I've tried using a different display/monitor and this didn't make any difference either. Looking at the graphs in PrecisionX, my GPU usage never hits 100% - both GPU's hover around 98% even when the fps drops below 60. I'm not sure if this is of any significance though. I have also set power management to 'prefer maximum performance' in the Nvidia control panel.

Please can someone help me - it's driving me crazy! :mad:

Many thanks in advance!! :)
 
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Could be your CPU getting bogged down the advanced draw calls.

With V-sync off the amount of rendered a head data and draw calls will fluctuate massively and could be bogging the CPU down.

With the frame rate capped the draw calls and stuff to render ahead should be smoother and more consistent give the CPU more breathing room.

Have you tried other drivers?
 
Hi almighty15, thanks for the help. I've only ever used NVidia's official drivers but have experienced this problem with every driver update.
 
jc0 said:
Hi almighty15, thanks for the help. I've only ever used NVidia's official drivers but have experienced this problem with every driver update.
Click to expand...

It sounds like it's your CPU struggling to keep up with the changing loads of the game.

Best way to check is to disable SLI and try it, if it's not as bad as a drop then it's CPU related.
 
OK thanks, I'll see what happens when I disable SLI. However, I would say that my CPU is water-cooled and overlocked to 4.6GHz - I'd be surprised if it was struggling to keep-up.
 
jc0 said:
OK thanks, I'll see what happens when I disable SLI. However, I would say that my CPU is water-cooled and overlocked to 4.6GHz - I'd be surprised if it was struggling to keep-up.
Click to expand...

It's still only a dual core though my friend, hyper threading will help it but at its heart it's only a 2 core CPU.

Adding graphics cards increases the amount of cycles a CPU needs for frame generation and that operation is what could be bringing performance down.

By turning SLI off you're giving the CPU some processing cycles back which it can use to generate frames at a higher rate thus giving you a better frame rate.
 
AC Unity doesn't work properly with sli, no amount of gpu or cpu power will make it smooth.

Though just to clarify you have an i5 750 or an i5 3570k?
 
Looks like it's an i5 750 , not i3 , think op mistake .... CPU should be enough overclocked .

I just think your uber sensitive to uneven framerates , if @ 60 is silky smooth I would say he fine CPU wise . You wouldnt get stutter @ 55 and not 60fps if CPU wasn't upto task.

I can't handle any drop below 60fps unless it's hard locked to 30 for example , it's the fluctuation in framerates that cause the stutter feeling

If your GPUs are properly taxed then it indicates your CPU is fine and not bottlnenecking .
 
almighty15 - I disabled SLI. As expected, I was unable to achieve 60fps (as I have everything set on ultra in FC4) but even at 46fps it was very juddery/stuttery - worse than with SLI enabled.

R400 - thanks for your input. Just to be clear - all games (including AC Unity) run perfectly smoothly for me as long as I'm achieving 60fps. But as soon as the framerate drops below 60fps, even by a few frames, the experience becomes jerky.

I have an i5 3750k.
 
MasterOC, I'm certain it's not just my sensitivity to uneven frame rates - the experience changes drastically when the fps drops below 60fps; anyone would notice it. The movement becomes judder and my mouse movements feel laggy - it's extremely noticeable. Then as soon as the fps goes back up to 60...it's instantly smooth as silk again.
 
opethdisciple said:
Two things here.

Most likely an i3 is underpowered for SLI.

And Unity is quite a bad game to judge performance in.
Click to expand...

opethdisiple - I have an i5, 3570k @ 4.6GHz.

The issue is in ALL games. They all (including AC Unity) run perfectly when maxing out at 60fps with v-sync on. As soon as it drops below, even just to 56 or 57fps, the smoothness disappears and it becomes a stuttery, laggy mess.
 
Telecaster said:
Could this be some other background program drawing performance away for a few moments, hence the slight dip in FPS and juddery play?
Click to expand...

No I don't think so because the dips don't happen at random; they'll occur, for example, when I'm looking at a particularly detailed area on FC4 with lots of foliage and detail etc. The frame rate will drop to, say 55fps and the gameplay will feel stuttery. Then i'll look away to a more 'simple' area, the fps will go back up to 60fps and the gameplay will feel smooth again.
 
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