MUYA
07-02-04, 06:26 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.
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.