unlocking GeForce 6800GS AGP

[Sa8Gecko]

I know this is not the right forum, but maybe someone stumbling on this by chance has the info I need.
I just bought such a card cause I've a old 478 mobo and cpu (P4B 2.8) and I wanted some better performance (I previously owned a 9800Pro). The card (contrary to the PCI-E version) is based on the 'old' NV40 chip (instead of NV42) and comes stock at 350 MHz core, 1000 MHz memory.
It has 12 pixels pipelines and 5 vertex pipelines enabled. What I did was enabling the 4 disabled pixel pipelines and the disabled vertex one using rivaTune.
I did some testing using 3DMark05: stock it comes at about 4300. Overclocking the core to 400 Mhz (without enabling the disabled pipelines) gives about 4725 (no visual artifacts).
Enabling the pipelines gives about 4850, but the standard driver don't let me overclock the core any more (it's stuck at 350). I've still to try Powerstrip, though. Visual artifacts (in the shape of black pixels) are barely visible in the 3DMark05 game test 3, Canyon flight. Now, since they are bearable, (and they don't appear in every game) and in view of such a great improvement in performance, the questions are these:
- can I leave safely all the pipelines enabled, without worrying about damaging the hardware (if some of you had bad experiences like the GPU dying after a while, let me know)
- can I attempt a little overclocking with these pipelines enabled ?

BTW: the 3Dmark05 demo song kicks ass !

[Sa8Gecko]

Some other info that may turn useful to owners of the same card.
First of all, check Guru3D.com forums. They're a mine of informations.
Second: the pixel shader pipeline I enabled was damaged (infact otherwise NVIDIA would have sold it as a GT...), infact after re-disabling it (but leaving the vertex shader pipeline, previously disabled, enabled) I was able to overclock again. Probably this is the situation in which most of the owner of this card will fall (remember, the AGP version, as the NV42 on PCI-e is a different story): maybe though someone gets lucky and have both disabled pipelines working OK.
For working OK I meant no visible artifacts are shown after enabling them. Anyway, simply enabling the vertex pipeline will give you about 150 more points in 3Dmark 05. Enabling the pixel pipeline should give you additional 400 points. All this without overclocking.
I was able to overclock the card, stable, to 410 core 1026 memory. Core temperature raised to 60-61 degrees under stress (from 39-40 idle). Really the core overclocked even higher (I went to 425) but then after a while it starts to spit out visual artifacts. Maybe with a better cooler I can go further. I don't want to raise the GPU core voltage, even if this could let me overclock higher and maybe get rid of the artifacts after enabling the disabling pixel pipeline.
Of course these results are not guaranteed for your own card. Maybe you can overclock higher (especially the memory), or not.
To back up what I'm saying, I'm going to post some 3Dmark 05 screenshots. My system is so composed:
- P4B 2.8 Ghz, 533 Mhz fsb
- mainboard abit BG7 intel 845G (yes, I know it's old, but I'm saving up for a new system after Conroe gets out)
- 1.5 GB PC2700 (DDR333)
- 6 maxtor HardDisks of various capacity, of which 2 in raid 0 and 2 in raid 1 (SATA)
- XFX GE6800GS (stock 350 core, 1000 memory)

Stock (12p/5v) core overclocked 400 Mhz:


16p/5v enabled, core 350, artifacts


16p/6v, core 350, artifacts


12p/5v core 425 mem 1000, artifacts:


12p/6v core 400 mem 1044, no artifacts


12p/6v core 410 mem 1026, no artifacts