The ASUS P5W64 WS Professional is a very unique board, based around the i975X, which means it could support Crossfire.  The board itself seems designed for a different use, as it seems the 8 monitor trick is being used a selling feature more than some kind of 4 card Crossfire, although it does leave space for a PCI-Express PPU.  The overclocking potential was not huge, at least not from the perspective of the tests X-bit Labs performed.
“Please meet ASUS P5W64 WS Professional Wall Street Quartet mainboard on i975X chipset that features four PCI-Express x16 slots that can accommodate four graphics cards and hence allow connecting 8 monitors to the system.”

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