They were unique products, because NVIDIA introduced 320-bit and 384-bit memory buses there for the first time.
These cards also came with 320 MB, 640 MB, and 768 MB of video memory, which was also a non-standard feature.
We are used to the 128-256-512-1024 MB sequence, while the G80 came with intermediate options. The 8800 GTX was very long, 270 mm, so it couldn't be installed in all PC cases.
The G80 GPU was huge, covered with a heavy cap. Data output units were implemented in a separate chip.
Read the rest of the article here