Bright Side Of News is reporting that PowerColor is launching a Radeon HD 5970 with 12 mini-DisplayPorts. Remember that the Radeon HD 5970 is comprised of two Cypress graphics processors connected by a PCI-Express bridge. A normal Radeon HD 5970 has a core clock of 750 MHz and a memory clock of 1000 MHz. This is slower than Radeon HD 5870 with a core clock of 850 MHz and a memory clock of 1200 MHz. Therefore there may be some headroom for improvement in the 12 mini-DisplayPort version of the HD 5870. Also, a normal Radeon HD 5970 would come with 2 GB of GDDR5 memory. This new version has 4 GB of GDDR5 memory. From the Bright Side Of News article:

Engineers at TUL Corporation showed real ingenuity by making full use of the six display pipelines inside each Cypress chip [i.e. “Hemlock”]. Their custom HD 5970 comes with 4GB GDDR5 memory of yet unspecified clocks, but the backplate reveals PowerColor linked each and every Display pipeline with mini-Display Port connectors.

via PowerColor to launch a 12 Display Card! @ Bright Side Of News*.