Theory for cabless crossfire with X1800 XT 256's

[fr4nk]

A complete copy from my thread over on Bit-tech (http://forums.bit-tech.net/showthread.php?t=117182)

Well as Highland3r should know (as I was talking to him about this yesterday) I've come up with a lil' theory for Cabless xfire on the X1800 XT 256's. As you know the X1800 GTO cards are useable in crossfire via drivers, not cables, no bridges you only need a ATi RD580 motherboard. The X1800 GTO's are also basically X1800 XL's with 4 locked pipes, what seems to be exactly the same PCB layout and some GTO's are also 16 pipe unlockable via a bios flash

So here's my threoy, either using a modded X1800 GTO bios that fully supports voltage control and 16p or mod a X1800 XT bios that has the P/N etc the same a GTO (as we need to keep the P/N etc numbers the same so the driver reconises the cards as a GTO). If it is possible to get this far I believe that crossfire should work via drivers. Thus having XT's in crossfire.

So my only consern is; does the R520 GTO core (or the card itself) have anything extra that would make crossfire work? Like something added to the arch (highly unlikely as the cards use XL core) or some added controlers? though whilst comparing the two cards I couldn't see anything differant physichally...

So I've been havign a play with bioses and rabit, and the best option would seem to be editign a XT bios leading the drivers to believe that XT is GTO which could possibly allow cabless crossfire but how would I go about editing the P/N ? I tried opening teh bios in notepad, I could see teh P/n (on teh top line) but if you edit it RaBit says "bios not ATi" so that doesn't work, maybe a hex editor ?

[Dippyskoodlez]

isnt it the device ID that signifys to the drivers what the card is?

[fr4nk]

As I'm aware of yes, but I think P/N will play a part in this too. I've managed to properly edit the P/N of my Xt bios (With a hex editor), checked with RaBit and it was fine, flashed fine, posted fine, showed the XP loading bar but after loading, no display, I heard it log on and everything I'm goign to try just a Device ID now...

[Dippyskoodlez]

Originally Posted by fr4nk

As I'm aware of yes, but I think P/N will play a part in this too. I've managed to properly edit the P/N of my Xt bios (With a hex editor), checked with RaBit and it was fine, flashed fine, posted fine, showed the XP loading bar but after loading, no display, I heard it log on and everything I'm goign to try just a Device ID now...

IIRC, all you should need to do is change the device ID to the other cards and it should detect as that card... assuming its drivers dont do anything different to "utilize it", it should work....

[Azn Tr14dZ]

Don't the X1800GTO's have an on-chip CrossFire bridge? That's what enables CF w/ out the Dongles...only drivers needed, which is 6.4 and later...

[cjoyce1980]

Originally Posted by Azn Tr14dZ

Don't the X1800GTO's have an on-chip CrossFire bridge? That's what enables CF w/ out the Dongles...only drivers needed, which is 6.4 and later...

That is very true, and all the newer ATI X1K series card have this chip, so unless you have this chip on your card, which leaves you up sh*t creek without a paddle.

Anyway with the next gen ATI cards, to enable crossfire, a dongle is gonna be used with all the new cards.

[fr4nk]

Would any one care to point out this chip ? heres two pics of the PCB's:
X1800 XT:


X1800 GTO:


Thanks

[W1zzard]

Originally Posted by Azn Tr14dZ

Don't the X1800GTO's have an on-chip CrossFire bridge? That's what enables CF w/ out the Dongles...only drivers needed, which is 6.4 and later...

if you are saying that the gto has some crossfire bridge inside the gpu silicon... that's not the case .. the gpus are identical.

any ati card can run crossfire without cables .. its just a matter of the driver enabling it

[Dippyskoodlez]

Originally Posted by W1zzard

if you are saying that the gto has some crossfire bridge inside the gpu silicon... that's not the case .. the gpus are identical.

any ati card can run crossfire without cables .. its just a matter of the driver enabling it

I think he has mistaken the Crossfire edition with the non CF edition- the CF edition has a chip for the dongle.

[POGE]

Someone should make some modded drivers to allow CF on any cards...

[fr4nk]

Originally Posted by POGE

Someone should make some modded drivers to allow CF on any cards...

hehe that would be nice, but its not exactly the easiest thing todo

[Dippyskoodlez]

Originally Posted by fr4nk

hehe that would be nice, but its not exactly the easiest thing todo

yeah

Really wish they woulda stuck with what they said originally with all X cards having xfire :'(

I was looking forward to Xfrie X700's lol

[warup89]

i think the only drivers that support dongless Crossfire are the 6.4 BETA right?

[cjoyce1980]

you need a pair of X1300 or X1600 for software enabled crossfire, all other cards require a crossfire master card

[2r4z0r2]

i managed to pair up two x1800xt 512mb cards without crossfire master

all i had to do is use x1800xl 512mb bios and flash it on both cards...afterwards i just upped the gpu voltage and modified memory timings to xt...got 8380 3dmarks06

motherboard is abit at8 32x

catalysts allow pairing up everything up to XT, but if u mod XL bios to xt speeds, u can work around it

[Azn Tr14dZ]

Originally Posted by cjoyce1980

you need a pair of X1300 or X1600 for software enabled crossfire, all other cards require a crossfire master card

X1800GTO's don't need the dongle.

Also, future CrossFire setups won't require a dongle, but a bridge, really similar to the ones that nVidia uses for SLI, but two of them towards the back of the PCB.

[Azn Tr14dZ]

Check this out:

[i_am_mustang_man]

i just want cf on my nforce4 sli board

but this is a really interesting thread