I got an answer from support:
>[Support - 12/10/2004 12:35:34] Hi, the difference between the clocks purely depends on manufacturers BIOS release and does not reflect >on the capability of the product. At the moment, all the 6800GT`s on the market are the same basic hardware spec. Indeed, the original >clocks speeds are not so crucial as they are designed to be adjustable with the coolbits supplied. Surprised your memory clock only goes to >941 though, and would normally suggest a hardware limitation. Can recommend BIOS `optimal` defaults and ensure good case ventilation. If >possible, use a dedicated power lead to the card and avoid a Y-splitter. Please ensure you have up-to-date mainboard BIOS and drivers >installed before the graphics drivers. Regards Tony
I have an Intel D865PERLK mobo with latest BIOS, Pentium 4 3.20E (Prescott), 1Gig DDR400, WD Raptor 36.7Gigs HDDand a 430W Antec TruePower Power supply... and yes my card is connected with a dedicated power lead and the inside of my case is never higher than 42oC.
I was able once to put it manually 500/1000MHz, but 80% of the time with coolbits2, I always just go to about 940MHz with having the test fail. If I do a autodetect overclock, I also only get to 936-951MHz.
My opinion is, these days the availability of DDR3 is not that good. XFX test their cards and if the memory is faulty at 1000MHz and can run just slightly lower than 1000MHz, they mod the BIOS to 900MHz and they get one more "good" card on the market. Maybe I'm wrong, you tell me!