I remember stories like that with some older motherboards and there was no cure since the board maker never released a new BIOS or patch to get the 8X slot to 8x.
Could be "one of those."
My ATI 9600 256mb sapphire atlantis is running a lot slower than it is supposed to. So i check out Catalyst Control center to see what my AGP speed is set at for my motherboard. it is currently set at off. so i try to change it to x8 which it is built for. but, my system deems the change unsafe and sets it back to off. is this a hardware problem or somthing i can do with software. (i need to change the AGP speed to x8) please help