Trying to understand CF microstuttering

E

eddieck

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I've been doing a lot of reading about microstuttering (considering a CF setup). I've never used a multi GPU setup before but I can already tell something like that would bother me to no end.

From what I understand all microstuttering is eliminated in Scissor mode. Am I right? I know the FPS won't be as good but at least it'll be smoother.

TIA!
 
well, I'm on a 5970 now, and I can't see it, im very picky too =p

Played MW2, Lineage 2, C&C4 beta, Sins of a Solar Empire
 
eddieck said:
I've been doing a lot of reading about microstuttering (considering a CF setup). I've never used a multi GPU setup before but I can already tell something like that would bother me to no end.

From what I understand all microstuttering is eliminated in Scissor mode. Am I right? I know the FPS won't be as good but at least it'll be smoother.

TIA!
Click to expand...

Yes, that's correct. Microstutter comes from AFR and variations in complexity from one frame to another. With Scissor, you get a more balanced use of the resources needed for each frame, and you should see less stutter.

But there are two downsides:

1. With Scissor, people report seeing a tear between the two regions of the screen drawn separately by the GPUs

2. You can only use one video card to calculate the geometry for a scene, so unless the game is shader-limited, you won't see perfect scaling.

The other way to get rid of microstutter and still use AFR is if you maintain a framerate well over 60fps. If your average is well over the 60Hz display rate of your monitor, then it won't matter if one frame is a little more complex than another - if they all get rendered faster than 1/60th of a second, your perceived framerate remains smooth.
 
defaultluser said:
1. With Scissor, people report seeing a tear between the two regions of the screen drawn separately by the GPUs
Click to expand...

I assume that's not the standard tearing that can be fixed by enabling VSync?

defaultluser said:
2. You can only use one video card to calculate the geometry for a scene, so unless the game is shader-limited, you won't see perfect scaling.
Click to expand...

What about supertiling mode? It would be cool if there was a way to use one card for antialiasing and the other for everything else.
 
Currently running two 5870's Crossfire at the moment, and I can quite honestly say I see no microstuttering at all. I was quite worried about it when I decided to go with a dual gpu setup for my new PC, but so far so good!
 
microstuttering isnt something you see as much as perceive it. defaultluser is right as long as you keep your fps above your monitor refresh rate it wont be perceived, this is why there is so much miss information and people saying " i have 2 gpu's and zero microstutter". I spend a couple weeks with 2 5850's and a 5870 before deciding to keep the 1 5870. The biggest deal breaker for me was in my office we had a gtx260 playing crysis, then my 5850's, even though I would be around 20fps higher than the 260 it would feel and look much slower on my system, it was like night and day side by side like that.
 
eddieck said:
I assume that's not the standard tearing that can be fixed by enabling VSync?
Click to expand...

It's caused by the two regions going at different framerates.

While not the norm, if one region's above 60 and the other's below 60 (not the norm, but possible), I would think v-sync wouldn't remedy this, unless it's v-syncing to the lower of the two. Even then, I'm not sure that would keep the two in sync.

I don't own one though, so I could be wrong. But I doubt v-sync's an absolute guarantee...
 
SoniCraze said:
The biggest deal breaker for me was in my office we had a gtx260 playing crysis, then my 5850's, even though I would be around 20fps higher than the 260 it would feel and look much slower on my system, it was like night and day side by side like that.
Click to expand...

Do you realize that you picked possibly the worst example of a modern game in terms of how well it works with crossfire? Crysis runs like crap on crossfire and to a lesser extent on ATI cards in general, due more than anything to the large amounts of money Nvidia shoveled at them to make it a TWIMTBP game.

If you are going to make hardware decisions based on one game you should do so with a game that isn't so heavily stacked in favor of one side. Quite simply put, performance with ATI crossfire in Crysis is NOT representative of your average crossfire gaming experience.
 
Digital Viper-X- said:
well, I'm on a 5970 now, and I can't see it, im very picky too =p

Played MW2, Lineage 2, C&C4 beta, Sins of a Solar Empire
Click to expand...

There's no Multi-GPU in Sins of a Solar Empire
that I saw. I ran it in SLI and Cross. It's such a cheap game to run visually...a faster CPU would improve performance.


I saw some bad microstuttering in Crysis Warhead in DX9, but it disappeared in DX10 with both a 4850 X2 and 4870 X2.
I have no idea why.:confused:
 
GotNoRice said:
Do you realize that you picked possibly the worst example of a modern game in terms of how well it works with crossfire? Crysis runs like crap on crossfire and to a lesser extent on ATI cards in general, due more than anything to the large amounts of money Nvidia shoveled at them to make it a TWIMTBP game.

If you are going to make hardware decisions based on one game you should do so with a game that isn't so heavily stacked in favor of one side. Quite simply put, performance with ATI crossfire in Crysis is NOT representative of your average crossfire gaming experience.
Click to expand...

Actually, ATI have been working their ass up for Crysis, it outperform nVidia's card on same level..

the multi-GPU setup for first game have some issue with certain point in game, like the harbor one that will stutter like crazy, either both nVidia and ATI have exact same issue.
its the game engine....

but in Warhead DX10 have no such issue at all... the stuttering in tunnel also gone in 5970 on my rig...
 
SoniCraze said:
microstuttering isnt something you see as much as perceive it. defaultluser is right as long as you keep your fps above your monitor refresh rate it wont be perceived, this is why there is so much miss information and people saying " i have 2 gpu's and zero microstutter". I spend a couple weeks with 2 5850's and a 5870 before deciding to keep the 1 5870. The biggest deal breaker for me was in my office we had a gtx260 playing crysis, then my 5850's, even though I would be around 20fps higher than the 260 it would feel and look much slower on my system, it was like night and day side by side like that.
Click to expand...

I don't perceive it even when the FPS does dip below the refresh rate, like in Crysis with the settings cranked up and various other system intensive games.
 
How does all this relate to Crossfire+Eyefinity stuttering?

In single screen Crossfire, I get no problems.
In Single GPU Eyefinity, I get no problems.

In Crossfinity there is really bad stutter. Napoleon, Anno 1404, Dirt2, Source games all stutter very badly on my 5970 in Crossfinity. You can see it perfectly just scrolling around maps in the first two games, or running in a straight line in source games.

My framerate in Team Fortress 2 is 220fps, in Crossfinity resolutions, so it's not like the added resolution is dipping my fps below 60 and making stutter more noticeable. Disable one GPU and it's silky smooth. It's the same with all those games I mentioned.
 
Sorry to revive a fairly old (~2-3 weeks) thread but I had another question and didn't want to start a brand new thread for it.

With AFR mode as long as I keep the frame rate above the monitor refresh rate there will be no perceivable microstuttering, right? I always enable VSync + triple buffering though, so my FPS would be capped at 60 (60 Hz LCD). As long as the GPU is capable of rendering more than 60 FPS (so if I turn off VSync and I'm getting 100 FPS) on a certain game then can I use VSync without any stuttering?

TIA!

edit: shit, meant AFR not scissor!
 
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Ogilvy said:
There's no Multi-GPU in Sins of a Solar Empire
that I saw. I ran it in SLI and Cross. It's such a cheap game to run visually...a faster CPU would improve performance.


I saw some bad microstuttering in Crysis Warhead in DX9, but it disappeared in DX10 with both a 4850 X2 and 4870 X2.
I have no idea why.:confused:
Click to expand...

well performance is fine in SINS for now :p
I also played DIRT 2.

but from reading that post about 2 regions, wouldn't AFR remedy that ?
 
i had some microstutter when i went crossfire. i found that afterburner was causing it. disabled it and voila. smooth as butter.
 
PrincessFrosty said:
This. I'm using the sapphire 5970 and dont "see" it, and I'm very picky about my gaming.
Click to expand...

If you could "see" it, it wouldn't be called "micro" stutter, it'd just be called stutter :p

Microstutter is simply that the percieved framerate is lower than what the game is telling you, because alternating frames take different amounts of time to render. The average may be better than a single card but what your brain percieves is actually the time it takes to render the slower image rather than the framerate shown by your computer.
 
Yeah, alot of people mistaking regular stutter for microstuttering. Like Rogue71, if afterburner was causing his stuttering, then it wasn't microstutter he was experiencing.

Generally, you don't really notice it until you're starting to get sub-30 fps. At that point, a single card running at the same fps as your crossfire setup will *feel* more smooth, because of the microstutter in SLI/CF configurations. That is why it's normally advisable to go with the faster single-GPU card over two slower cards for SLI/CF.
 
If your on the side of the fence that doesn't think you can "feel" a difference between 40 fps and 60fps then sli/crossfire will be fine for you. If you can feel the difference between 60-80 or even 80-100 then stick with a single gpu setup.
 
SoniCraze said:
If your on the side of the fence that doesn't think you can "feel" a difference between 40 fps and 60fps then sli/crossfire will be fine for you. If you can feel the difference between 60-80 or even 80-100 then stick with a single gpu setup.
Click to expand...

I am very sensitive to fps, but I can say I have NEVER encounter a micro-stuttering EVER since 9800GX2 and 3870X2...
 
Raap said:
Yeah, alot of people mistaking regular stutter for microstuttering. Like Rogue71, if afterburner was causing his stuttering, then it wasn't microstutter he was experiencing.

Generally, you don't really notice it until you're starting to get sub-30 fps. At that point, a single card running at the same fps as your crossfire setup will *feel* more smooth, because of the microstutter in SLI/CF configurations. That is why it's normally advisable to go with the faster single-GPU card over two slower cards for SLI/CF.
Click to expand...

i assumed it was microstutter as it was very intermittent small stutters but it was enough to notice. glad to know i just had a case of the plain old stutters.
 
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