Power, Temperature and Noise
Remember how we wrote about the potential for a dual-GPU card based around two GTX 780s? We believe that it's possible once Nvidia screens for the very best frequency/voltage GPUs. Two separate cards push system-wide consumption up to 420W, but, going by previous experiences, this should be reduced to around 375W for a two-GPU board.
The Titan-like cooling works an absolute treat when in SLI. Two cards remain very, very quiet, almost absurdly so.