I've read such and found the documentation to never actually be written in the words you supplied. I have however found that documentation to write "1.5V supply required for 8X operation."
Please supply the link to your passage so we can tell.
In closing, there is no AGP 8X only card out there because... they would not sell.
The 8500 will work in 1, 2, 4 and 8X slots that it fits into.
I just purchased a Fujitsu-Siemens D1675-WB motherboard. The manual states that a AGP 1.5v display board must be used or damage to the display adapter and/or motherboard will result. I want to use my ATI All-in-wonder 8500 128Meg display board with this motherboard. Can I do this? The Fujitsu and the ATI sites don't have any answers and they have not replied to my emails. I found some information on the web about AGP and the 8500 has both the 3.3v and the 1.5v keys. But I'm still not sure about this.
Richard R. Johnson