I have a 648Max 8xAGP with a GeForce Ti-4800 which is also an 8xAGP, but when checking it always shows 4x as the bus speed, how can I change this, I have tried the card on a different 8xAGP motherboard and it showed the correct speed.
I wouldn't even try. To begin with, it won't help performance. Add to that, it might cause stability issues with your board.
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