Geforce 6800 Ultra and GT PCIe are based on the good old NV40 core paired with BR2. Nvidia calls it NV45. Nvidia was happy to tell us before that Nvidia managed to overclock NV40 AGP interface from 8X to 12 X or faster. With this overclock, Nvidia managed to match the AGP8X chip speed with 16X PCIe interface and make a chip which is almost as fast as the native PCIe one.
Now for the consequences. It seems that not all of the NV40 chips, especially the fastest one clocked at 350 or 400MHz, manage to work with BR2 chip overclocked to 12 X AGP. That might explain the shortage.
This could mean that BR2, HSI chip was not so great after all. Time will tell but I don't expect to see much more 6800 PCIe cards in the future. I guess that Nvidia might solve high end PCIe card shortage problem once it introduce native PCIe card. This will happen sooner or later. µ
Sign up for INQbot – a weekly roundup of the best from the INQ