Yes, problem is evident in dualcard configs in XP or Vista, 32-bit or 64bit, Vista shows same problems with 3-4 cards as well.
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Yes, problem is evident in dualcard configs in XP or Vista, 32-bit or 64bit, Vista shows same problems with 3-4 cards as well.
What about SLi and CrossFire on linux?
rofl. Are you serious? PLease tell me you are not. I can't see why you are asking this question....there is no Linux Crossfire driver.
I'm not sure about crossfire, but there's definitely an SLi driver for Linux.
Please refrain from being patronizing.
Sry, man. I humbly apologize. there's just no games for linux..most are windows, so the need for Crossfire on linux is very small.
I DIDN't know there was SLi for linux...I'm actually quite surprised. I wonder why they've invested time in that?
nvidia always supported linux
ATI's linux newer drivers are open sourced, so crossfire might turn out eventually.
linux has official ports: Doom3, serious sam, UT2k4, Enemy Territory: Quake Wars,
and Unreal3 is coming soon
+wine and cedega of course
it's not DEAD :)
no, but I've never had Linux in my mind as an option for graphics rendering...power computing. Guess maybe I'll have re-evaluate that!
Wow!!!!! That explains all of the constant stuttering problems I experience with my games when using my 7900GTX-SLI PC instead of my other 8800GTX PC.
My favorite racing game, Test Drive Unlimited, is unplayable on 7900GTX SLI, although it can run at 35 fps sustained. The constant stuttering just does not look good at all, and looks more like 15 or 20 fps. Many other newer games also stutter more than on my 8800GTX.
makes sense to me. on P35 x4 is connected via the southbridge to the northbridge and therefore has a higher latency.Quote:
Originally Posted by generics_user
if you get a stutter ever 5 minutes, then thats NOT caused by the dual videocards. micro stutering is constant, what you experience is caused by your system memory beeing full and the game has to read/write data from/to the hdd ;)
Just wanted to Bump this and let everyone know that the new 8.4 drivers didn't resolve this issue :(. I guess I'll put them on ebay and buy an nVidia card.
single GPU FTW! :D
Yep. School of hard knocks i guess :\.
Yeah, I've always preferred single card too.
if you're gamign @ 1600x1200 or higher (which you should be, anything lower and a single midrange card should be fine for you) sell the GTX and get a 8800GTS 1gb or wait for 9800GT 1gb
Has this been fixed ever on the nVidia side, or still a constant issue?
Funny thing is when I force split-frame rendering, it seems to help a bit with the "micro" stuttering. However, SFR does not work for some games and I have to suffer severe micro-stuttering (and additional lag) with AFR mode in Test Drive Unlimited, UT3 and Bioshock, COD4, Transformers, ETQW, and most of the newer games.
So I use my 8800GTX for those (except for ETQW).
sure, sfr should improve the situation a lot, stuttering should only appear when one of the gpus needs more time for its part of the frame than originally planned. if sli is perfectionized then sfr or atis tile mode should cause no micro stuttering at all.
wot a kick in the arse for multicards :|
does running cards at exact same clocks help? does it only happen in some games?:shrug: just curious as ive never run crossfire.
it would be helpful to have a list of games for 2, 3 and 4 card/gpu setups which work with absolutely no problems. it looks like a can of worms to me.
Is there a game, where it is certain this phenomenon can be observed with nVIDIA SLI?
Some SLI supported games mentioned I have played personally, with and without SLI, and there is no doubt to me, that all of them felt more smoothly with SLI than without.
Quote:
Originally Posted by saaya
Please explain how that would ever give a less smooth experience than:
1:00:01 frame 1
...
1:00:31 frame 2
...
I really don't understand it, so please (someone) explain it to me. If the above is the correct explanation, then worst case scenario would be the same as without SLI, right?
I don't think the above explanation is the correct one, or at least not the complete one.
Hopefully the r700 won't have this issue by sharing the memory bus
When there an even gap between frames your mind tend to fill in the blanks, so as long as your getting sufficient frame rates it appears smooth. With uneven gaps between frames you become aware of the uneven motion even if your getting more frames than required for what we would consider smooth motion.Quote:
Originally Posted by Seraphiel
30fps with even gaps can appear smooth, wheras the uneven gaps are noticable even with very high frame rates. This can mean that playing a game with a single card at 30fps could appear smoother than playing a game in sli at 60+fps.
it affects sli AND xfire, it happens in ALL games...Quote:
Originally Posted by adamsleath
its just more apparent in some games compared to others...
i already explained it 2 times, did you read the entire thread? :PQuote:
Originally Posted by Seraphiel
ok... here we go again :D
if you draw a cartoon you need a certain amount of pics per second to show to make it look fluent, right? well you can make things look more fluent by doubling the frames. you just show each frame twice, that actually does look more fluent even though you dont get more information.
BUT, this only works if you insert the frames propperly and show them exactly between the other frames. what happens with sli and xifre now is that the extra frames that the second or third/fourth gpu adds, are not displayed or rendered in their propper time windows.
its a bit difficitcult to understand, i admit that...
its basically a bad syncing of game time and frame time.
essentially the stuttering is caused by the game time not matching the frame time, so when we actually see the frames, they dont show a constant flow of time between the different frames, but it stutters.
a movement isnt steady but from one frame to the other the game appears to run slightly faster, then slightly slower. it happens so fast that we perceive it as stuttering.
i dont know... i dont think you need new hardware to get it to run propperly...Quote:
Originally Posted by AliG
its possible with topdays cards to adjust the frame times, but... it means less performance.
maybe with new gpus they find a way to do adjust frame times without a perfomance impact... hopefully!
Does this also happen with the GX2's and X2's?
Well, in Saaya's example the delay was constant (0.00.03), but even if it wasn't so, I am not sure that it would give a less smooth experience. Also, framerates can be pretty inconsistent when playing a game. I wish there was an easy way to actually test the theory.Quote:
Originally Posted by onewingedangel
That actually makes sense to me, if it means that the frames observed are not in sync with what they "should be" (1.00.01 frame are shown at 1.00.01, but frame 1.00.04 are shown at 1.00.06, frame 1.00.07 are shown at 1.00.07, but frame 1.00.10 are shown at 1.00.12 etc.) ?Quote:
Originally Posted by saaya
And if they were in sync, even if irregular/inconsistent, then it would still be more smooth if more frames were rendered, right ?
Yes, I did read all of the thread. Could be me that just don't get it :)
Still, I personally haven't experienced this with SLI, so perhaps it is OS/driver/game etc. related and not a general problem. Wouldn't it be a problem in all games for all CF/SLI users, if that wasn't the case?
No it wasn't, look again.Quote:
Originally Posted by Seraphiel
1:00:01 frame 1
0:00:03 gap
1:00:04 frame 2
0:00:27 gap
1:00:31 frame 3
0:00:03 gap
1:00:34 frame 4
Using a single GPU when at 30fps theres a specific gap between frames (1/30 second), and when at 70fps whilst the gap is different (1/70 second), its still a consistant rate between frames. When you transition between frame counts you notice this as speed up or speed down, but either way it is still smooth as the gap between frames is consistant with the ammount of frames rendered.Quote:
Originally Posted by Seraphiel
With the AFR multi gpu approach the timing between frames can be inconsistant hence appearing as stuttering. Look at the example below:
EG. Single GPU
FRAME1 >30ms> FRAME2 >30ms> FRAME3 >30ms> FRAME4
EG.AFR
FRAME1 >10ms> FRAME2>20ms>FRAME3>10ms>FRAME4>20ms>FRAME5>10ms>FRAME6>20ms>FRAME7
Even though your getting additional frames from the second GPU its the timing of those frames that causes the stuttering. Under ideal circumstances the gap between the frames should be consistant at 15ms.
Add into that that the speed up and slow down experienced when the fps changes isn't neccesarily consistant between the to GPU's and the gap between the frames can be thrown out by an inconsistant rate, which further complicates things.
Theres some new leaked Catalyst drivers out. I wonder if they fix the micro stuttering issue...
http://www.station-drivers.com/page/ati%20catalyst.htm
Those do fix the stutters, at least for me in Crysis.
saaya
that's a bummer, but im sorta grateful that there is another reason NOT to double up on gcards.Quote:
it affects sli AND xfire, it happens in ALL games...
its just more apparent in some games compared to others...
i would really like the sli/cf thing to work well, but i found it to be flawed, surely there are circumstances where sli and cf work flawlessly?
yes, with sfr and tile mode there should be less stuttering.
especially with tile mode, cause with tile mode, in theory, you can always split the frame in 50% and 50% of the work that needs to be done and each gpu can then finish rendering its tiles in the same time. this should assure a constant frametime. and also! the gpus work on the same frames together, making it virtually appear as one gpu to the game! so there wont be any game time or frame time issues caused by splitting up the work and distributing it amongst several gpus. this technique is especially interesting because a single gpu already works that way in some regards.
afaik ati gpus internally break down each frame into tiles of 8x8 or 16x16 pixels iirc, nvidia gpus instead break down each frame into rectangular horizontal stripes of 20x2 pixels or something like that, and then each part of the gpu is then working on such a chunk of data.
so tile mode would basically mean extending this technique to several gpus. unfortunately it seems its not easy to master and get it working right with a high latency and limited bandwidth link between the gpus.
gpus have a massive bandwidth to their memory of 150gb/s, but dont forget, the internal bandwidth between all the parts of a gpu is way beyond that!
getting both gpus to work as one would either require a massive bus link, and even then youd have a latency impact, or, you need to find a way to share as little data as possible and compress data as good as they can. compressing data and managing huge amounts of data is one of the most important things in gpu tech afaik. there are rumors that with Rv7xx there will be some fast connection between the gpus.
Im thinking they might share some of the memory, which basically means they use a part of the memory controller to create a link between both gpus.
Again, modern gpus have a mem bandwidth of up to 150gb/s and they use 8 memory chips, so thats 18gb/s per chip roughly.
If they share one of the 8 chips, then this would be as fast as having 16 pciE lanes only for both gpus to talk to each other...
and since the memory controllers are connected indirectly, this might even be more effcient, since the gpu can probably access and work with data faster if its already in the memory compared to receiving it through the pciE interface and then loading it to memory.
anyways, im drifting off topic :D
seraphiel, i know what you mean, why is adding frames a bad thing, it wont be as good as having 2x the original frames cause of the issues, but it should still be better than having only frames from one card. well, your right... but... it seems having a constant frametime seems to be more important than a high frame rate.
and im starting to think that the real issues people are seeing here are actually caused by the gametime delays from one frame to the other.
there is always a delay from the time a gpu starts to work on a new frame, and basically works on that snapshot of that game time, until its finished and then displayed. it seems that if you use certain post processing effects or a game is programmed in a certain way, then one gpu needs longer from snapshot of the gametime until it finished the frame.
maybe in some games or scenarios you always need to base the next frame on the previous one for some special effects? and to speed this up, ati and nvidia maybe do it like this: gpu1 renders one frame after the other recycling its own frames, gpu2 always recycles the frames from gpu1 to create the next frame.
and as a result the frame times and game times are not matching anymore?
that would actually be a different issue than what i previously explained, but it would describe the issues people are seeing here much better.
as it seems to be limited to only some games and stuttering a lot more and... rougher, than what youd expect from real micro stuttering based on inconsistent frame times alone