Crossfire limitation
- Thread starter Slappi
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EDIT: Too little sleep...
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JoshMST said:
lol. Good point, Josh. I missed your post up there.
Josh,
that "Knee-jerk reaction" commit was not a very good one nor accurate IMHO. Sure there are some limitations. But there are also some neat things that SLI is not able to deal with or was not at first. The new "super AA" modes (and I know NV matched them now, but ATI was first to annouce it) and no profiles needed (and yes I know it only takes a few moments to add a profilem but no matter what NOT having to add one is an advatange like it or not) are two things that help it stand out. Usally knee jerk reactions seldom have anything new to add to the mix. Cross fire does.
that "Knee-jerk reaction" commit was not a very good one nor accurate IMHO. Sure there are some limitations. But there are also some neat things that SLI is not able to deal with or was not at first. The new "super AA" modes (and I know NV matched them now, but ATI was first to annouce it) and no profiles needed (and yes I know it only takes a few moments to add a profilem but no matter what NOT having to add one is an advatange like it or not) are two things that help it stand out. Usally knee jerk reactions seldom have anything new to add to the mix. Cross fire does.
jb... the more I dig into this, the more interesting things I pull up.
Crossfire is supposed to bring good features, but there are some serious questions about if it delivers.
SuperAA is rumored not to be able to work with OpenGL titles yet, only D3D. I do not have a CrossFire setup, so I can't test this out. This is just something that I have heard and have heard repeated by others. It could be absolute FUD for all I know, but it is something that is out there.
SuperTiling may not work with odd numbered quad cards. So if a person has a 12 pp Pro version, it will not support SuperTiling.
SuperTiling will be the default rendering mode... unless Catalyst AI says that it would work better with Scissor mode or alternating frame mode. Sounds a bit like profiles to me? Throw in the issue about odd numbered quad cards...
Also, it appears that the compositing engine doesn't have any built in RAMDACs or TMDS transmitter, so it has to rely on external devices... which I am guessing is the reason that Crossfire does not actually work above 1600x1200 at this time (a little bird I trust, and not from the green camp, has verified this to me).
Crossfire is supposed to bring good features, but there are some serious questions about if it delivers.
SuperAA is rumored not to be able to work with OpenGL titles yet, only D3D. I do not have a CrossFire setup, so I can't test this out. This is just something that I have heard and have heard repeated by others. It could be absolute FUD for all I know, but it is something that is out there.
SuperTiling may not work with odd numbered quad cards. So if a person has a 12 pp Pro version, it will not support SuperTiling.
SuperTiling will be the default rendering mode... unless Catalyst AI says that it would work better with Scissor mode or alternating frame mode. Sounds a bit like profiles to me? Throw in the issue about odd numbered quad cards...
Also, it appears that the compositing engine doesn't have any built in RAMDACs or TMDS transmitter, so it has to rely on external devices... which I am guessing is the reason that Crossfire does not actually work above 1600x1200 at this time (a little bird I trust, and not from the green camp, has verified this to me).
jb said:
The no-profile thing is just hype - if they want to get the best out of their hardware they will need profiles. And not having to enable a default mode in the control panel is not any advantage to speak of given the user base for dual-GPU configurations.
I've always said that Crossfire's only avenue for victory is its abilitiy to accelerate more titles and features than Nvidia's SLI.
jb said:
I agree that a lot of thought and engineering work has gone into CrossFire, but the R series of graphics chips were never designed for a desktop multi-GPU solution. Yes, they are used in professional simulators and whatnot (with the SuperTiling support), but those are definitely not consumer level products.
ATI took what they had, and tried to make a cost effective way to deliver multi-GPU products to the consumer market. Again, the GPU's were not designed at the chip level to handle such things.
So, I don't think "knee-jerk" is out of line. If ATI had taken their time and created a GPU that didn't need a compositing chip, or an external dongle, then I would gladly take that comment back.
But that would have take a lot longer to bring to the market as the R5xx was too far in the design process to add that type of tech to it. Thus they would have even later with their products which would have caused even more "ATI is late" comments. ATI was dammed if the do, dammed if the don't. So meh...
Yeah, they are kinda damned both ways, but which one would have been easier to handle? I think ATI might have been better off leaving the multi-GPU platform to NVIDIA until they could get a true competitor. How much time, money, and engineering resources have been dedicated to CrossFire? Its a hell of a balancing act, and hindsight is of course always 20/20. If I were in charge there, I know I would have given the go ahead for CrossFire development because I am an enthusiast and a tech optimist. It is just starting to look like the limitations of such a platform could eventually overwhelm it and lead to some disappointing results.
Haha, didn't NVIDIA learn their lesson about doing things half-assed with a product not that long ago?
Haha, didn't NVIDIA learn their lesson about doing things half-assed with a product not that long ago?
JoshMST said:
I think the most obvious validation of this stance is the fact that they tried to bring Crossfire to the X800 line. Even the R520 implementation seems to be tacked on. So yes, it was a "knee-jerk" response to Nvidia's SLI. Can't blame them though - that would have been two generations without a dual-GPU solution - a big marketing no-no.
JoshMST said:
Josh, who briefing you on this? I've heard the same stuff repeated a number of times recently, but none of it is new.
What issue is there if SuperTiling doesn't operate with 12 pipe boards? If it produces results whether it works or not is immaterial, and that its probably going to be the same if it was "tacked on" or not. As for the game profiles, NVIDIA brought this up at their editors day, and I don't understand what potential issues there are here - ATI has always said that they would default some games to different modes, but these aren't openly profiled, but hardcoded (curiously they openly state that you can change the mode by turning Cat AI off and playing with it, although I've not figured that one out yet); there is still a default, but some are coded in the drivers, just like other game specific code they have in Cat AI. And, no, the OpenGL SuperTiling thing is not correct - there is a specific issue I have noted, but I've tested another OpenGL title and it works fine (yes, I've got an image difference between 6x and 14x).
As for the compositing device - the graphics chips themselves can actually do the work. Current drivers for SuperTiling don't use the composite engine at all, the pass their data across the PCI Express bus and the master graphics chip does the compositing. This being the case, with their next generation boards they have the opportunity to remove the compositing device and go for an internal connection connecting both the graphics chips together - if they don't do this, and still have the compositing engine, then they must have some reasons for not doing doing it.
Well, obviously ATI isn't breifing me, or I wouldn't be able to talk about it.
You are correct, none of this is really new, but I think that we are finally starting to see the bigger picture. The release is apparently right around the corner.
In many ways your post leaves me a bit confused, as I agree with most of what you say. My point with profiles is that ATI says, "We won't have profiles" but Cat AI will be deciding which titles get which rendering method. I don't think there is anything inherently good or bad with profiles or AI, it is just the way these companies do the job. It is interesting to read that you haven't been able to disable Cat AI. If there is one person that knows 3d graphics, it is definitely you.
I am really glad to hear SuperAA works with OpenGL, as I had been somewhat confused why OpenGL wouldn't work but Direct3D would. Just didn't make much sense to me.
Again, I am looking at this from the point of view of an outsider. I have not been given any special access or any official information on CrossFire. This is information that I have tried to glean from other sources. Just doin the best I can with what I got.
One other thing... you are absolutely correct aobut the external RAMDAC. I was not aware that the outputs for the master cards had to be run through an external RAMDAC when I wrote my little deal up. 240 MHz ain't terribly fast anymore...
You are correct, none of this is really new, but I think that we are finally starting to see the bigger picture. The release is apparently right around the corner.
In many ways your post leaves me a bit confused, as I agree with most of what you say. My point with profiles is that ATI says, "We won't have profiles" but Cat AI will be deciding which titles get which rendering method. I don't think there is anything inherently good or bad with profiles or AI, it is just the way these companies do the job. It is interesting to read that you haven't been able to disable Cat AI. If there is one person that knows 3d graphics, it is definitely you.
I am really glad to hear SuperAA works with OpenGL, as I had been somewhat confused why OpenGL wouldn't work but Direct3D would. Just didn't make much sense to me.
Again, I am looking at this from the point of view of an outsider. I have not been given any special access or any official information on CrossFire. This is information that I have tried to glean from other sources. Just doin the best I can with what I got.
One other thing... you are absolutely correct aobut the external RAMDAC. I was not aware that the outputs for the master cards had to be run through an external RAMDAC when I wrote my little deal up. 240 MHz ain't terribly fast anymore...
