Details of AMD's upcoming Radeon HD 7990 6GB dual-GPU have leaked, ahead of a rumoured August launch date, revealing an interesting approach to power regulation.AMD's answer to rival Nvidia's GeForce GTX 690, the Radeon HD 7990 6GB is rumoured to pack two Tahiti XT graphics cores alongside a total of 6GB of GDDR5 memory running at 1,500MHz on a PCI Express 3.0 high-end graphics board. With those kind of figures, AMD is going to need some serious power - and a leak claims to reveal how it plans to get it.According to anonymous sources speaking to VR-Zone , the Radeon HD 7990 6GB is to include four six-pin power connectors rather than the more common two eight-pin connectors. The reason for this somewhat odd decision, the site's sources claim, is power regulation through a multiphase system split into three groups: one for the GPUs, one for the memory, and one for the PCI Express controller itself.The site's sources also indicate that the board will include six display outputs: four mini-DisplayPorts and two DVI connections. Support for all the multifarious AMD technologies, including EyeFinity and HD3D, will naturally form part of the system.So far, AMD is keeping quiet on the accuracy of the rumour. While it has already confessed it's working on a dual-GPU design to knock Nvidia's GTX 690 from the top spot, it's keeping firm details quiet - largely, it is claimed, due to a schedule slip from an originally planned June sampling. With sources giving August as the earliest possible launch date, but not preferring a likelihood of the board actually arriving before Christmas, we could have a while to wait in order to see if the rumours are true.