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View Full Version : 6800 Non Ultra 3 Quad GPU moded to 4 Quad 6800 Ultra/GT?


MUYA
07-02-04, 07:26 AM
http://www.ixbt-labs.com/articles2/gffx/nv40-3-p1.html

Check it out
Obviously, only the on-die markings are different. We don't know for now if they contain information on the number of enabled pipelines or the chip name is immediately stuck to the cover during the check of broken pipelines, and the marking is put on the die afterwards (NVIDIA employees definitely have to know which chip they're dealing with).

Having coped my long-lingering doubts, I once decided to supply GeForce 6800 with a GeForce 6800 Ultra BIOS. It is generally possible as, in contrast to ATI, NVIDIA does not set strict parameters of memory timings and size in BIOS.

During the experiment, GeForce 6800-to-Ultra memory size was read correctly (128MB), but the frequency couldn't be fixed at 700, and the display showed garbage (indicative of overstated frequencies). Through it, I could see Windows identify the card as Ultra, but as it was impossible to work, I reinstalled the right BIOS. All the frequencies have restored and the card works all right, but... there is just one but.

Some tests started to show artefacts in the form of broken lines, which clearly meant something was wrong with the card. What was the most puzzling is that it only revealed in some tests. Such complex ones as FarCry, TRAoD, etc. run perfectly, but Splinter Cell and RtCW had these artefacts followed by a total hang.

The answer came when I looked at the results of the tests that worked. Performance increased compared to the original GeForce 6800! The fillrate test (3DMark03) showed that the number of pipelines remained 16! That is, 6800 BIOS hadn't brought the 12-pipeline state back! The reason for this lies probably in 6800 Ultra BIOS which can reprogram certain elements (chip registers, for example) and which obviously changed the number of pipelines. 6800 BIOS can do none of that, so the number of pipelines remained the same. Probably, it just checks the number in such a way that if it is not smaller than the necessary one (12), than BIOS changes nothing.

So, the question remains open and perhaps, our ubiquitous Alexey Nikolaichuk will find out the reason and work it all out.

I managed to find an answer why such complex things as FarCry do not damage the card while old ones can't work. Those four pipelines that were disabled and that I enabled are just partially, not completely broken. Perhaps, it affected some parts (like texturing caches) which are not used by FarCry, while all shader units remained workable. But we're leaving this issue for the moment and will be waiting for new information on this account to appear.

991060
07-02-04, 07:32 AM
My friend once flashed a non-ultra, 3dmark score boosts. But the card crashed in a few fillrate tests.

MUYA
07-02-04, 07:36 AM
I still am sceptical but if anyone can hunt down the underlieing mechanism to mod a 6800 NU to a full 4 quad 6800 GT/Ultra, it's gotta be uniwinder.

anzak
07-02-04, 07:38 AM
Chris, you have a new project. :thumbsup:

Jedi Rainman
07-02-04, 12:31 PM
Good luck and keep us posted.

mikechai
07-02-04, 01:19 PM
As the GeForce 6800NU uses a different PCB and has only 128MB ram, it is unlikely flashing with ultra or GT bios will work.

On the other hand, I'm sure the GT can be flashed to a full fledge Ultra. :)

CaptNKILL
07-02-04, 01:33 PM
As the GeForce 6800NU uses a different PCB and has only 128MB ram, it is unlikely flashing with ultra or GT bios will work.

On the other hand, I'm sure the GT can be flashed to a full fledge Ultra. :)
OK, first of all, 6800 to Ultra has worked (read the post!), and second, all you have to do is overclock the GT to get an Ultra, they have the same amount of pipelines.

oh ya, the GT and Ultra PCBs are also different :retard:

kahloq
07-02-04, 01:58 PM
You guys also need to remember that even tho the Ultra bios did unlock the 4 pipes on that 6800NU , they were not completely intact. Once you do it, tho, you cannot lock those 4 pipes back up if you get graphics problems because theres nothing in the 6800NU bios to close pipes down, it jsut checks for 12 pipes present.

JayrodTremonki
07-02-04, 05:03 PM
As the GeForce 6800NU uses a different PCB and has only 128MB ram, it is unlikely flashing with ultra or GT bios will work.

On the other hand, I'm sure the GT can be flashed to a full fledge Ultra. :)

Flashing with different amounts of RAM is no problem, my 5900 NU(128MB) flashed to 5950(supposed to have 256) no problem. DDR3 vs. DDR might, on the other hand.

ChrisRay
07-02-04, 05:09 PM
Chris, you have a new project. :thumbsup:

Eh.. I aint breaking my card with conclusions like this. He did say after flashing back the card did not function properly. Forgive me for not wishing to Guinea Pig this.

I value the card too much.

kahloq
07-02-04, 05:45 PM
Do not blame you at all Chris

anzak
07-02-04, 10:07 PM
He did say after flashing back the card did not function properly.

True.

Diamond_G
08-12-04, 04:13 PM
any updates?? i'm looking to get a nu cause my xp2400 would hamper the gt/ultra too much

Lfctony
08-12-04, 05:00 PM
I'm with Chris on this one, its not like its a softmod and you can just unistall the driver.

BYUNews
08-12-04, 06:38 PM
Isn't there a RivaTuner version coming soon that will (possibly) allow a 16-pipe 6800NU softmod? I scanned the RT forums, and the author said that this might take a few weeks, but I know it exists.

Diamond_G
08-12-04, 08:18 PM
i'm not gonna mod the bios... just picked up that last pny 6800nu on island for 312... there is a place here asking 400 for it (before taxes.... sheesh)... but that place is high any way (PC Connections in Hawaii... right next to Compusa)

I just want to keep my options open for opening up the other pipes....