I wouldn't be surprised if NVIDIA at least stop producing dual GPU cards from now on, no word of the GTX 990 and also a single PCB you need to have space for 2 GPU's (obviously) their VRAM and power delivery, there is only so much space on there and not to forget about the cooling. Two single GPU cards have roughly the same size PCB (give or take) yet a lot more space for power delivery and the cooling system has an easier time. They just seem to be a huge waste of money because two seperate cards of the same or similar class with perform better.
I love dual GPU cards (9800 GX2, 295, 590) but their single GPU counterparts perform better out of the box, you still have SLI issues so that is no loss or gain but the GPU runs at higher clocks. Anyone remember the Titan Z, what a piece of shit for £2,500 lol
Anyway I'm tired and thinking about the Titan Z has pissed me off a little. Struggling to read through what I've wrote, time for bed.