ATI Radeon HD 4000 Series discussion

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06-15-2008, 07:20 AM
Genius_pt

Quote:

Originally Posted by Luka_Aveiro

micro-stuttering is the result of AFR solutions, and it happens due to each gpu frames synchronization.

Example:

GPU1-> frames 1,3,5,7,9,11,13 @ 0,01sec 0,05 0,09 0,13, 0,17 0,21 0,25

GPU2-> frames 2,4,6,8,10,12,14 @ 0,02sec, 0,06 ,010 0,14 0,18 0,22 0,26

If you come to notice, there is a 0,03sec gap between GPU1 and GPU2 frames, and that's the micro stuttering thing, while you have 2 frames displayed by each gpu one imediatly after another, but then you have a 0,03 gap.

This is just a quick example nothing really deep.

Nice read.

Thanks for the explanation :up:.
06-15-2008, 07:27 AM
Xello

Am i right in thinking that if they 'solved' this problem, and sync'd the frames, there would likely be a sizable performance hit? Reminds me of V-sync.

If that's the case, perhaps they just don't want to do this, with SLI and XF scaling already being far from perfect.
06-15-2008, 07:27 AM
pest

Quote:

Originally Posted by Luka_Aveiro

micro-stuttering is the result of AFR solutions, and it happens due to each gpu frames synchronization.

Example:

GPU1-> frames 1,3,5,7,9,11,13 @ 0,01sec 0,05 0,09 0,13, 0,17 0,21 0,25

GPU2-> frames 2,4,6,8,10,12,14 @ 0,02sec, 0,06 ,010 0,14 0,18 0,22 0,26

If you come to notice, there is a 0,03sec gap between GPU1 and GPU2 frames, and that's the micro stuttering thing, while you have 2 frames displayed by each gpu one imediatly after another, but then you have a 0,03 gap.

This is just a quick example nothing really deep.

I hope we mean both the same thing.
I've made ton of graphs visualizing microstuttering, and it appears in cascades. For example the frametime-differences alternate beetween 10 and 60ms.

this stutters
http://www.abload.de/img/crysis_cf_on_2t9w.jpg

this not
http://www.abload.de/img/crysis_cf_on_34r1.jpg

Quote:

Originally Posted by trinibwoy

Read what I wrote again. How is "the CPU delivering the processing data too fast" different to "the frames are not distributed evenly in game time" ? Obviously game time is controlled by the CPU. Don't argue just for arguing sake...a little reading comprehension goes a long way.

Because the unevenly distributed frames are a result of the too fast cpu :yepp:
cold is the result of viruses...i don't have a problem understanding this
but this is a way too ot for now
06-15-2008, 08:45 AM
trinibwoy

Quote:

Originally Posted by Luka_Aveiro

micro-stuttering is the result of AFR solutions, and it happens due to each gpu frames synchronization.

Hopefully these diagrams can make it a bit clearer for those who are interested.

http://img301.imageshack.us/img301/7051/gpuafrbe0.jpg

http://img119.imageshack.us/img119/3627/cpuafriy8.jpg
06-15-2008, 08:49 AM
SEA

It is clear with different frame times.

The only thing nobody explains - why would the frames be so different all the time in the middle of game? I would understand they differ at the moments of begining of changes of picture like new big object appears on the screen. But! next frame would still have it! If you say that object changed position/size and next frame would require more processing? -Ok. But it supposes to remain on next frame(s)! So time difference should spread over all consequent frames pretty evenly...

So it should not stutter?!
06-15-2008, 08:58 AM
flippin_waffles

Apples and oranges here but, as AMD are practically masters of interconnects would it be out of the question that the graphics group has leveraged some of that knowledge to improve core to core communication? They are the same company after all.
06-15-2008, 09:03 AM
trinibwoy

Quote:

Originally Posted by SEA

It is clear with different frame times.

The only thing nobody explains - why would the frames be so different all the time in the middle of game? I would understand they differ at the moments of begining of changes of picture like new big object appears on the screen. But! next frame would still have it! If you say that object changed position/size and next frame would require more processing? -Ok. But it supposes to remain on next frame(s)! So time difference should spread over all consequent frames pretty evenly...

So it should not stutter?!

Depends on the game. In something like a racing game where the game world is going by rapidly and the view is changing at a high speed the stuttering can be very noticeable. In an RTS or RPG and most FPS's it won't be that noticeable. And the issue isnt about how long it takes to render the frame on each GPU. It's about the timing of when frames are delivered to each GPU and how long each rendered frame stays on screen.

The problem with it isn't only that you notice it. The other big problem is that the big fps numbers are false. In some scenarios (highly GPU limited) you're getting essentially the same frame rendered twice in a row followed by a long delay then two similiar frames rendered in short time etc. That's why some people find single GPU play "smoother" even though the FPS numbers are lower.

AFR doesn't work well in extremely GPU (frames thrown away, stuttering) or CPU limited situations (no scaling). The sweet spot is somewhere in the middle (my second diagram above).
06-15-2008, 09:04 AM
-= rtz =-

Sry if this has been posted but,its a 100 pages thread :)

Does anyone know will accelero S1 fit on 4870 since it fits on 3870?
06-15-2008, 09:42 AM
ripken204

the mounting seems to be the same as the 3870 so i would have to say yes
06-15-2008, 10:15 AM
GAR

Is the 4870 coming out on june 25th as well?????
06-15-2008, 10:35 AM
LordEC911

Quote:

Originally Posted by GAR

Is the 4870 coming out on june 25th as well?????

Wasn't it the 23rd? But yes that was the reason for the one week delay.
06-15-2008, 10:45 AM
STaRGaZeR

And still nothing about the 70. No leaked bench, no nothing. :(
06-15-2008, 11:13 AM
Hornet331

Quote:

Originally Posted by STaRGaZeR

And still nothing about the 70. No leaked bench, no nothing. :(

lol there are allready guys that have bought the 4850 and have them in there hands, head over to 3dcenter or hwluxx forum. :p:

http://www.forumdeluxx.de/forum/show...495808&page=62
06-15-2008, 11:15 AM
zerazax

He meant the 4870 i think but thanks for the link

Looks like 4850's are in a lot of retailers hands already, some just want an early head start on them sales ;)
06-15-2008, 11:21 AM
STaRGaZeR

Quote:

Originally Posted by Hornet331

lol there are allready guys that have bought the 4850 and have them in there hands, head over to 3dcenter or hwluxx forum. :p:

http://www.forumdeluxx.de/forum/show...495808&page=62

70 :p:
06-15-2008, 12:40 PM
GAR

I dont see how the 4870 would launch at the same time as the 4850, no pics no benchs, i find it hard to believe that it will launch the same time.
06-15-2008, 01:45 PM
JameCa

well we will se right :)?
06-15-2008, 01:51 PM
GAR

Quote:

Originally Posted by JameCa

well we will se right :)?

We sure will, in 10 days......damn, seems like sucha long time :ROTF:
06-15-2008, 01:59 PM
w0mbat

New GPU-Z: http://www.techpowerup.com/downloads...-Z_v0.2.4.html

Quote:

Originally Posted by GPU-Z 0.2.4

Improved RV770 detection
06-15-2008, 02:00 PM
Helmore

Quote:

Originally Posted by w0mbat

New GPU-Z: http://www.techpowerup.com/downloads...-Z_v0.2.4.html

Improved |= Perfected, but still I want to know what it will show us now...:cool:
06-15-2008, 02:03 PM
w0mbat

me2, that why i posted it here. I hope someone w/ a HD4800 card will use it and show a validation/ss.
06-15-2008, 02:12 PM
Eson

Quote:

Originally Posted by flippin_waffles

Apples and oranges here but, as AMD are practically masters of interconnects would it be out of the question that the graphics group has leveraged some of that knowledge to improve core to core communication? They are the same company after all.

Shintai says its more or less impossible to make such interconnect, therefor it will never happend. :rolleyes:

But the engineers surely has thought of this and i hope we will see it soon because i think its more likely to happend then not.
06-15-2008, 02:18 PM
Luka_Aveiro

Quote:

Originally Posted by pest

I hope we mean both the same thing.
I've made ton of graphs visualizing microstuttering, and it appears in cascades. For example the frametime-differences alternate beetween 10 and 60ms.

Man, I just made a quick example, nothing very deep, so yap, your example is perfect, I just made through a quick mind example nothing more.

Actually, micro-stuttering is a very easy deal to understand :)
06-15-2008, 02:30 PM
Hornet331

Quote:

Originally Posted by Luka_Aveiro

Man, I just made a quick example, nothing very deep, so yap, your example is perfect, I just made through a quick mind example nothing more.

Actually, micro-stuttering is a very easy deal to understand :)

maybe, but both ati and nvidia ignored it for several years now. :p:
06-15-2008, 02:34 PM
Helmore

Quote:

Originally Posted by Hornet331

maybe, but both ati and nvidia ignored it for several years now. :p:

Doubt it, but if they did than this could imply that micro-stuttering is a rather easy thing to fix through drivers. If they already knew about it for a while, let's say at least a year, then the fix is probably not very easy.

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