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  #11 (permalink)  
Old August 19, 2008, 02:52 PM
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beats me. I don't see anything, but I'm old and half blind now.....
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  #12 (permalink)  
Old August 19, 2008, 03:05 PM
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I must have bad eyes as well. I didn't see the microstutter.
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Old August 19, 2008, 03:10 PM
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Heh. Well, it's there, and it affects alot of apps. You can check my youtube page, and see some comments from those that DO SEE IT in the video I posted. I try to not say much about it, as it has been completely been blown out of proportion as of late(alot of websites reporting microstutter show other issues), but it does exist.

I'm fairly confident that I have found the cause as well, and should I be right, the XSP may help with the 4870x2, when enabled, but 3- and 4-card crossfire will still suffer.

It's a very specific symptom of a specific problem, and alot of sites jsut generalize performance issues as Microstutter.

I've spent alot of time dealing with the problem since Crossfire's inception in the public marketplace, and over generations of Crossfire the problem has not changed much. But there's a difference from an app not having a crossfire profile(which many sites call Microstutter) to having a profile and the displayed framerate by application or FRAPS fps counters not matching the framerate displayed on the monitor.

Anyway, I've promised more than just here to take the video of DMC4, so I'll do that in a couple of hours, and then will post it up. That may be a bit easier for you guys to spot.
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Old August 19, 2008, 03:49 PM
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geez in the scope of things, don't you think you can just ignore it and direct your energy to something meaningful? I've been running crossfire for a long time, 3 generations in a row, and have never noticed anything like this. If the game runs too slow, lower the settings or install another video card.
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Old August 19, 2008, 03:55 PM
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So, from what you've put together, what's the real cause of the microstuttering? I used to be reading up on it, back when I was screwing around with a 3870X2 and couldn't figure out what the hell was going on. But I've kind of given up at this point, and just decided to avoid multi-card altogether.
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Old August 19, 2008, 04:36 PM
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Quote:
Originally Posted by vinister View Post
geez in the scope of things, don't you think you can just ignore it and direct your energy to something meaningful? I've been running crossfire for a long time, 3 generations in a row, and have never noticed anything like this. If the game runs too slow, lower the settings or install another video card.
That's the problem. Lowering settings, and thereby increasing the framerate, make the problem WORSE. And there is NO installing another VGA..I have 4 gpus now, as it is. And it has nothing to do with an app running slow...the faster the app runs, the bigger the problem.

Basically there is not enough bandwidth between the cards for third and fourth cards to properly send thier rendered frames to primary gpu, and then out to the monitor. This lack of bandwidth is what causes the problem, but it can also be partially fixed if the driver drops the right frames...and sends only the needed ones(keeping in mind that 60FPS, matching monitor refresh rates, is usually almost eonugh) With 2 gpus the issue is there, but it's barely noticible. When framerates go tooo high though, it will rear it's ugly head, even with just 2 gpus. Unfortuantely, 2 gpus are not currently enough to push the 2560x1600 res of my 30" monitor.

You understand, I'm now running 2x 3870x2. If you look @ my hwbot profile, you'll also see that I've been running Crossfire since X850...so X850, X1900, X1950, HD2900, and now HD3870x2's. I've also got nVidia 7800GTXSLi, 8800GTX SLi, and they had issues as well. This is NOT a problem confined to ATI/AMD cards...it's confined to multi-gpu rendering!

I would have remained with a single 3870x2, but considering 2x 2900XT is a bit faster due to the extra memory bandwidth, and I had issues with that, I had hoped that the addition of the second 3870x2 might solve my issues...but it made them worse.

It's unfortunate that you think this issue is not meaningful, but unless the problem it brought out into public focus, it's not going to be one that companies deal with. If they are not aware of issues, they aren't going to spend any R&D dollars in fixing the problem.


I'm not your avg user...I fall into the "extreme enthusiast" category, and issues I have are issues that I relate to others who may consider buying lesser products...and as such, after a few years, my voice DOES get heard by OEMs, as I can influence at least a few prospective buyers. AMD called me up at home over the 2900XT UVD fiasco...that was shocking, to be honest. A foxconn agent sent me a BlackOPs for my b-day...after I complained that the 33 million people here in Canada were being ignored.

So, it IS meaningful, and sometimes I do get results.


But this Microstuttering issue, one that I started talking about back in X1900 days, isn't like others, and yes, it's blown out of proportion. AMD has openly admitted to the problem, and the XSP is the 4870x2's is the answer to the problem.


It's just too bad, that it won't work for 3- and 4-card Crossfire, and that they will be victims of Microstutter as well...but at least we have progress.

Last edited by cadaveca; August 19, 2008 at 04:41 PM. Reason: spelling
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Old August 19, 2008, 05:47 PM
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Quote:
Originally Posted by MpG View Post
So, from what you've put together, what's the real cause of the microstuttering? I used to be reading up on it, back when I was screwing around with a 3870X2 and couldn't figure out what the hell was going on. But I've kind of given up at this point, and just decided to avoid multi-card altogether.
Same here, I'm sticking with with single gpu, as hard as it is (it's hard not to run out and snag a 4870X2) until there is something revolutionary that gets rid of this problem as well as others I have with the multi-gpu platform (driver issues, profiles etc etc.) I've used SLI from every series since it's inception, the 3870X2 was the first side of the ATI kick at the cat, both solutions display it depending on the situation, and not all people see it or the problem is generalised to something else. Perhaps if XSP ever get's sorted out properly, probably on the next generation from ATI it will go away, but from what I've read, as long as AFR is being used this isn't going to go away, despite how minute it might be.
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Old August 19, 2008, 07:22 PM
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one god is good with me....
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  #19 (permalink)  
Old August 20, 2008, 07:07 AM
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Its not about the frame rate, its about the length of time between frames being displayed. Microstuttering is a problem, and I witnessed it somewhat because of a bottleneck in the P5K-E.

It occurs on games that usually bottleneck cards and is not restricted to crossfire.
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  #20 (permalink)  
Old August 20, 2008, 08:39 AM
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Um, P5K-e? with one 16x slot, and one 4x slot? Yet another bandwidth bottleneck? How is that any different?

It has NOTHING to do with the length of time for the frame to be displayed. It has everything to do with all the drawn frames not being displayed, and what you describe is a DIFFERENT problem from Microstutter, and hence alot of the confusion.

Yes, the behavior may appear like Microstutter, but that problem you describe is quite different from Microstutter with 2x 16-lane PCI-E 2.0.

This is why this is such a touchy subject...the problem you describe can be fixed by using a board with 2x 16-lane slots. Easy fix. Toss in a couple of X1950's which will not use the full bandwidth of the slots, but use the TMDS chips for compositing the image, and you'll still have Microstutter, because the TMDS chips are not capable of dealing with each and every frame...

You can look at it this way...crossfire bridge has 1gigabit connection. Note the BIT and not BYTE.

At 2560x1600, a single frame can consume 25mb or more. Even if it is BYTE, 60FPSx25MB=1500MB...already exceeding the bandwith of the connection, should it be BYTE, by 50%. Which frames get there by the bridge, and which don't? Which ones are sent over the pci-e bus, with greater latency? And with variable framerates, how is this managed?

There's far more to this issue than most think, unfortunately, because Microstutter, as I've already said, is a specific symptom of a specific problem. Solve YOUR problem, which is easily done with another board, and you'd still have stutter. Ergo, the pci-e lanes bandwidth is NOT the problem, as solving that problem did not sovle the stutter.

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