SLI issues/concerns and stuttering (GTX 200, 8, and 9 Series)

[Eliminator]

Originally Posted by mailman2

Thats the micro stutter everyone is talking about.

well then its a misleading word because it doesnt feel like its skipping or stuttering... just not smooth

[Bman212121]

Originally Posted by tdream

Can the people who have no issues state what monitor resolution they use and what cards they have.

See sig, VIM.

Dell 2407WFP A03 (I think)
1920 x 1200 @ 60hz
Evga 8800GTX SLI stock clocked (575/1350/900)

[SH64]

Not stuttering , but i'm 99% sure the AFR latency issue is still there. (which is the main reason i'm not interested in SLI/XF anymore)

[Vanzagar]

wow, I'm kinda suprised how flat the poll is, I don't think I've ever seen a poll without any one choice over 25%? Well I guess this pretty much clinches it that I will stay away from SLI, especially given all the stuttering votes... one last question is Crossfire about the same, better or worse?

Thanks,

rh

[SH64]

Most likely the same since it uses AFR as its main profile for its multi-GPU rendering.

[brunner]

I switch from 8800GTX SLI to 280GTX SLI and so far there've been far less stuttering. It's not a placebo effect for sure. The stuttering was very obvious in Dirt regardless of which drivers I use. I was not able to duplicate the stuttering so far. Dark Messiah is another game which has obviously stuttering. So far, everything seems to have a lot less of the typical hitching and stuttering that is common in PC games. I wonder if it's because of the combination of massive bandwidth + 1gb.

[spajdr]

Also enablind triple buffering under DX9/DX10 makes it pretty all much smooth.

[Revs]

No real problems, some stuttering but rarely and not enough to annoy me. The GT's and these GTX260 have very good scaling with 70-100% being normal. I went back to a single card a few months ago because I got a P5K mobo but I only lasted a week before I went back to SLI. I thinks it's superb and wouldn't be without now. Drivers are getting better all the time, too.

I played Crysis last night with about 30-60FPS avg and it was very smooth. I didn't notice any real stuttering at all.

[MikeC]

Originally Posted by Bman212121

I can't say as I've had many issues with it at all. I don't recall a game where SLI caused stuttering. I've had stuttering in COD2 & 4 if you don't set the options for multiple video cards even if you only have one, and I've had stuttering in several games right when dual core came out, but I can't remember a time where SLI was to blame.

I have on used SLI on a pair of 6800GT's and my 8800GTX cards, so it is possible I've dodged the bullet from other setups. 6800GTs where quite mature by the time I ran SLi with them so a lot of the problems were likely already solved.

The only times I've seen where SLI didn't help is if the game was already able to run all out on one card. UT2k4 paired with an 8800GTX comes to mind, it is already sitting on the frame cap so you really can't go much faster. In a case like that you still have the option to turn on SLI AA modes and get even better IQ.

Another thing that used to be a big concern for everyone was having profiles for all of the games. For the most part everything runs great with AFR2 so IMO that gets rid of a lot of the need to even mess with the profiles at all. You can just use the global setting to force everything to use AFR2 if you want, but most games are already setup with the correct rendering method. I have only came across one game that for some reason is set in the drivers to use split frame, so I just change that to AFR2 and it runs even better.

+ 1

[MikeC]

Originally Posted by tdream

Can the people who have no issues state what monitor resolution they use and what cards they have.

2560x1600 using mixed-vendor SLI with graphics cards from a number of add-in partners such as EVGA, MSI, Inno3D, and XFX.

[Kaguya]

Installed a pair of GTX 260s a couple hours ago and so far so good. Tried all my games, and things seem smooth. Only problem I had was Grid was giving me micro-stutters but after doing some reading on micro-stutters I went ahead and turned VSync on for Grid and it smoothed out.

[101]

I've used SLI with 7800 GTXs, 7900 GTXs and now the 280s. It has certainly come a long way over the years but is by no means perfect. My biggest remaining issue is the frame jitter, which is what many call "micro-stutters". It is easily demonstrated in the following example.

This is a benchmark of TF2 run with vsync enabled where 18,000 frames were captured from an online demo of a few minutes in length. Frametimes were logged using fraps, converted into individual frame display times, and finally converted to hertz. This final value is essentially instantaneous framerate, or the constant framerate you would achieve if all frames were displayed in the time it took for a given sample.

Instead of plotting a bunch of useless squiggly lines, this data was then converted into a histogram. Only framerates between 50 and 70 were considered to remove loading issues or whatever, and it was then binned at 50 mHz to provide adequate resolution.

The resultant plots illustrate how many frames fell at a given instantaneous framerate. The ideal trace in this example would be an impulse function occuring exactly at 60Hz with no additional frames falling anywhere else. As can plainly be seen in the SLI case, the jitter that occurs when the frames are recombined causes "spreading" about the target vsynced rate. Significantly more than the single card case.

Keep in mind the total frames are the same, and if you integrate each curve you get roughly the same answer. The disabled case provides 1.022 M framecount*Hz, while the enabled is 988K framecount*Hz, or great efficiency at only 3% overhead.

The variance in displayed framerate, induced by the jitter caused by SLI is what people have termed "micro-stuttering". Granted not everyone can see it, just like some people can't tell the difference between 30Hz and 60Hz, but if you can it's rather distracting.