AMD Quad FX processors and compatible motherboard are now available for consumers to buy, but only if you have the cash.
Having done some research I can only find the Quad FX CPUs and the ASUS L1N64-SLI WS motherboards at Newegg and ZipZoomfly. Both retailers stock the whole range of Quad FX CPUs and prices at Newegg are as follows:
Over on ZipZoomfly the prices are marginally lower:
Prices for the ASUS L1N64-SLI WS are also high. It comes in at $429.99 at Newegg and $379.99 at ZipZoomfly. Putting this together it means that two FX-72 processors and a compatible motherboard would set you back nearly $1,500. On top of that you need RAM, a decent graphics card, an insane PSU, and of course Windows Vista Ultimate to support the whole thing.
At the end of all that spending you get a pricey rig which offers dubious benefits.[poll id=60]