ATi Radeon X850, X700 & X300 On CrossFire!

[malware]

HKEPC, has successfully to decipher how the whole ATI Crossfire concept actually works. As a result, they are able to run two slaves cards in Crossfire without the need for the Crossfire edition master card. The amazing feat they have done was to run X850, X700 and X300SE HM on Crossfire! However, this doesn't come easy at all as it took them a month to reverse engineered the BIOS and Catalyst drivers to make it work. This has proven one thing; Composition engine is only needed for proper image composition not for performance or Crossfire capability between two cards is determine through chipset and drivers.

Read Full Story at HKEPC

View at TechPowerUp Main Site

 

[boruvka]

Wow - if this is true (my Mandarin is, sadly, not good enough to read the actual article) I already regret having bought the wrong mainboard and video card

But how does it work? A composition of the image is still needed, but do I guess correctly that only the "Master"-Card has a loop-through-function? How do they put the image "together"? A Y-cable and prayers?

 

[grazzhoppa]

. This has proven one thing; Composition engine is only needed for proper image composition not for performance or Crossfire capability between two cards is determine through chipset and drivers.

Does that mean the image produced on a monitor will be garbled or only show 1 card's output? So lets say if you used the method of splitting the rendering in half, you'd only see half of the rendered frame? And if you used ATI's tiling method, you're monitor would be a checkboard of black space and rendered scene

You might see some way to hack a method for some external composition engine that could combine the 2 cards' images in the near future

I can't read HKEPC's site, so I am very curious.

 

[gR3iF]

what me scares are the people who buys then a crossfire setup without cr card and then trys to flash it on a nforce 4 board or something

 

[W1zzard]

Does that mean the image produced on a monitor will be garbled or only show 1 card's output? So lets say if you used the method of splitting the rendering in half, you'd only see half of the rendered frame? And if you used ATI's tiling method, you're monitor would be a checkboard of black space and rendered scene

that's exactly how it's gonna be .. but at least you can bench cards in this setup .. its of no real world use ..

if anybody has ideas how one could compose the images without additional hardware i'm open to ideas

 

[mixa]

The results shown in the graph are veryyyy suspicious.I have ASUS EAX700 and it scores 7600 at 3Dm03 at stock speeds and 8500 when overclocked.I can`t belive the results are correct.

 

[malware]

The results shown in the graph are veryyyy suspicious.I have ASUS EAX700 and it scores 7600 at 3Dm03 at stock speeds and 8500 when overclocked.I can`t belive the results are correct.

Look at the mainboard(Grandmars RD480 Eng Sample). It's a Eng. Sample of an eng. sample chipset, and nobody knows what's the real performance compared to your nForce(2, 3, 4, 4SLI i guess) mobo.

 

[mixa]

I guess you`re right

 

[gR3iF]

wizz i guess there is a chip for comparing the two cards in one picture and that is what crossfire is all about??

 

[Unregistered]

Composition Engine is required on Tile Mode and Split Frame Mode only.
For Alternative Frame Mode (like the Voodoo2) only Y-cable is needed.

However, due to IP reasons, ATI cannot use it without a license.

 

[Unregistered]

Composition Engine is required on Tile Mode and Split Frame Mode only.
For Alternative Frame Mode (like the Voodoo2) only Y-cable is needed.

However, due to IP reasons, ATI cannot use it without a license.

IP for what? AFR?

ATI's previous dual card the old Rage Maxx used AFR so they don't need a license.

And 3dfx used Scan line interleave, not Alternate Frame rendering.

 

[mashie]

I'm curious how well the cards are synchronised regarding the DVI output. Considering they are all digital they could be quite good. Now if anyone can make a DVI Y cable with fast AND/OR gates to merge the signal to the monitor it would be very very interesting...

W1zzard, sounds like a challenge for you

 

[W1zzard]

i dont think there is an easy way to do an y cable that is properly synced ..anybody good with the inner works of dvi ?

 

[mashie]

i dont think there is an easy way to do an y cable that is properly synced ..anybody good with the inner works of dvi ?

Well the specification can be found here.

 

[stordoff]

the images on the site show a full screen display

 

[grazzhoppa]

the images on the site show a full screen display

That's because its just showing the Windows desktop. Crossfire isn't enabled all the time - its just when there's a 3D app running. Sort of like antialiasing or anisotropic filtering, they run only when directx or opengl calls for it.

 

[stordoff]

oh, that explains it

 

[Unregistered]

If I'm correct the x700PRO cards are around $170 - $200.
One X800PRO (XT-PE depending on your luck) is around $399 depending on actial product!
So what would make me get two x700PRO cards that are slower together than an ordinary X800PRO that can (some times) be moded to XT-PE?

 

[alpha732]

I see x700pro refurbs for $99 and new for $115

 

[MADawg]

Mixa I have the same video card-an EAX700 Asus. Curious to know what your overclock speeds were?

 

[nick255]

With all these new developments do you think it will be possible to hack crossfire vc bios/drivers to work on an sli board instead of a crossfire board?

Are there any hardware reasons as to why crossfire wouldnt work on an sli board (ati have obviously put something in place to make sure it only works on a cf board), does the ati chipset do any extra processing etc? to make crossfire possible.

 

[ShadowFlare]

If ATI wanted to, they could maybe add support for sending the image over the PCI Express bus and then doing the compositing somewhere along the way. Maybe it could be a type of overlay that would be used to minimize the amount of work the rest of the computer has to do?