Asus A8R-MVP CrossFire Motherboard
 

Rather than using a small PCB in a slot on the board to change between
single and dual card mode, the A8R-MVP uses a small piece of PCB that
slots in to the top slot. This disables this slot and transfers the
bandwidth to the lower slot to make this a full x16 slot. It’s a simple
solution but it works well. The downside is that you can’t use the slot
at all in single card mode, something most SLI boards allows you to at
reduced bandwidth.

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