Crossfire uses profiles, same as SLI

[Rollo]

http://www.techreport.com/etc/2005q2/ati-crossfire/index.x?pg=1

After talking to ATI's Catalyst driver team, we learned that although CrossFire's Direct3D and OpenGL defaults allow it to accelerate any application, the drivers will also ship with application-specific profiles. These profiles generally use Alternate Frame Rendering, which apparently offers better performance than superTiling or scissor modes. However, AFR apparently can't be blindly enabled without the danger of causing display corruption or stability problems, so scissor and supertiling modes provide good fallback positions for games that lack AFR profiles.

So much for "Catalyst AI" making on the fly evaluations of what works best with games- the only difference between this and SLI is that SLIs default fall back for a non profiled game is single card, Crossfire has tiling for D3d or Scissors for OpenGL. (BTW- you can set the default mode for SLI with Coolbits enabled as well)

What about ATIs scissor mode? I've heard that it's not the same as SLIs-

The ATI SFR mode can split the frame horizontally or vertically but it is not dynamic. In other words, ATI drivers predetermine the split. On SLI, we can dynamically shift the split to even out the balance in real-time based on varying dynamic workload across both SLI cards.

I got this info directly from nVidia, so I have no link.

In any case, I find it amusing that ATI is trying to lead us to believe their is some behind the scenes evaluation of each game going on, where it's really just a. looking for a profile b. if not finding one defaulting to tile or scissors based on whether the app is OpenGL or D3d. (bear in mind defaulting to a mode doesn't guarantee it offers benefit or works well)

 

[Jbirney]

In any case, I find it amusing that ATI is trying to lead us to believe their is some behind the scenes evaluation of each game going on, where it's really just a. looking for a profile b. if not finding one defaulting to tile or scissors based on whether the app is OpenGL or D3d. (bear in mind defaulting to a mode doesn't guarantee it offers benefit or works well)

Umm most of us here already new this as it was stated in many places that it would use profiles...

 

[pxc]

Umm most of us here already new this as it was stated in many places that it would use profiles...

But just yesterday the resident f-boys were posting it wouldn't.

 

[Met-AL]

Well no shit it's going to use profiles. Why would you need to have "Catalyst A.I." do a bunch of tests to figure out what is the best method to run a game every time it's run? It's gonna be the same everytime, so why not just load a profile? Profiles are the smart way to go.

 

[ZenOps]

Profiles are basically the same thing as application detection. Its just that the *application detection* name has an evil aura surrounding it.

I'm not surprised in the least if ATi Crossfire uses *.exe detection and then picks the maximal rendering mode for that application, it would be no different then SLI in that respect. Whatever gives you the best results - I say use it.

Crossfire looks like a good step up from SLI, but both still leave a lot to improve upon.

 

[Jbirney]

But just yesterday the resident f-boys were posting it wouldn't.

So why is this post any better then theirs?

 

[pxc]

So why is this post any better then theirs?

because this is true and that wasn't?

 

[1c3d0g]

@ Jbirney: because now all of a sudden profiles are "O.K."?

Hahaha, there truly are hypocrites on this site...

 

[Spank]

What about ATIs scissor mode? I've heard that it's not the same as SLIs

The ATI SFR mode can split the frame horizontally or vertically but it is not dynamic. In other words, ATI drivers predetermine the split. On SLI, we can dynamically shift the split to even out the balance in real-time based on varying dynamic workload across both SLI cards.

A plain vertical/horizontal split could be the smart thing to do to avoid cpu overhead in cpu limited games.

some reviews are stating that it's dynamic, [H] for example, other reviews says its a fixed split. maybe Ati havent made up there mind about how they will do it.

(bear in mind defaulting to a mode doesn't guarantee it offers benefit or works well)

If none of ati's 4 rendering modes works with a game you can always increase the aa to 8x from 4x with just a tiny performance hit. so you will always get some sort of a benefit with crossfire.