X1900 CrossFire ?BiosMod? Problem with other 256MB Card

[Rebound]

Hi there. Im having bad crossfire results.

Here is my problem:

I have a x1900xt 256mb from the past.
I recently got a x1900 512mb crossfire master card, to do crossfire!

Problem:
- The slave card (x1900xt 256mb) only has 256mb

- So crossfire only assumes 256mb!

I though he was going to use 512mb (mastercard) + 256 (slave).

But he uses 256 + 256



I was thinking in a bios mod for my 256mb slave card.



HOW:
- Not bios mod all the card or flash the memory
- Only change the adress info that sends the information about the card memory size.


RESUMING OBJECTIVE:
- Change bios information, ONLY INFORMATION, to say: i have 512mb.

Maybe this way, crossfire would assume 512mb crossfire

But how to do this?

EDIT: Ive used ATI Tool 0.26, saved Slave card BIOS (the 256mb one), download Rabit, but i have locked the option to change the memory size :(

[Zubasa]

Hi there. Im having bad crossfire results.

Here is my problem:

I have a x1900xt 256mb from the past.
I recently got a x1900 512mb crossfire master card, to do crossfire!

Problem:
- The slave card (x1900xt 256mb) only has 256mb

- So crossfire only assumes 256mb!

I though he was going to use 512mb (mastercard) + 256 (slave).

But he uses 256 + 256



I was thinking in a bios mod for my 256mb slave card.



HOW:
- Not bios mod all the card or flash the memory
- Only change the adress info that sends the information about the card memory size.


RESUMING OBJECTIVE:
- Change bios information, ONLY INFORMATION, to say: i have 512mb.

Maybe this way, crossfire would assume 512mb crossfire

But how to do this?

EDIT: Ive used ATI Tool 0.26, saved Slave card BIOS (the 256mb one), download Rabit, but i have locked the option to change the memory size :(

Dude, you will hardly finish the 512MB on you cards :respect:
Just because a GF8800GTX has 768MB, doesn't mean you will need it!

[Namslas90]

According to ATI, the card registers as 256mb memory but the extra memory is actually used as a sort of 'page file' to preload information to get in line to be processed; sort of like a 'prefetch.

[AthlonX2]

try switching the cards in there pcie slots

[INSTG8R]

its pretty much operating as it should. No BIOS mod will let it use more memory. Your the first CF user I have come across that has done the mismatched memory sizing TBH, but it is functioning as advertised.you are still seeing CF in action but yes its sad you lost some usable memory.

[boecke]

Maybe support will come for this in the future, I doubt it though.. ATI is lazy ass.

[Rebound]

Thanks for answers.

Its stupid i now! But i will give you an example for how many performance im loosing with this:

TEST 1 --> Only one PCIe (Mastercard X1900CF Edition 512Mb @ 680/830)
--> Slave card not connected (x1900Xt 256Mb)

3dMark06 - SM2 - 2876 points
- SM3 - 3642 points´

On TomsHardware a X1900XT 512mb card should do:
-SM2 - 2468
-SM3 - 3044

Conclusion: Using single card a lit bit overclocled i can do more points than the ones reported on tomsharware.






TEST 2 --> PCIe 1 (Mastercard X1900CF Edition 512Mb @ 680/830)
--> PCIe 2 (Slave card x1900Xt 256Mb @ 680/830)
--> Crossfire only assuming 256Mb:banghead: (why doest it assume 768?)

3dMark06 - SM2 - 3900 points
- SM3 - 4300 points´

On TomsHardware a X1900XT 512mb card should do:
-SM2 - 4208
-SM3 - 4936

Conclusion: Using Crossfire setup EVEN with overclock i cant do more points than the ones reported on tomsharware. An thats stupid! On single card i did it...