If you're using multiple W600s, you can have 12 monitors all at once, you just can't create an Eyefinity grouping of all 12 monitors (so that you have 1 massive screen made up of 12 monitors). You can definitely extend to all 12 though and this can be done through the Catalyst Pro Control Center (which comes with the drivers), you just need 2 PCIe x16 slots (2.0 or 3.0), a 500W or higher Power Supply, and either direct Mini DIsplayPort-to-DisplayPort connections for the monitors, or that you utilize at least 4 active adapters from www.amd.com/dongles for each card (so 2 passive per card max).
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