Power Consumption
The GTX 280 is well known for its high power requirements. Based on the same circuit design, we’d expect the mildly-crippled GTX 260 Core 216 GPU and slightly-slower GDDR3 DRAM to increase power consumption simply because three, rather than two, cards were used.
Though the 3-way graphics solution does draw more power, the actual difference is surprisingly small. One could argue that the 3-way GTX 260 Core 216 solution is even more efficient, since it has an even greater lead in computational power, but its performance lead in games was limited to a single title.