When Intel released the i7 last year, all of the memory manufacturers immediately answered with low-voltage triple channel DDR3 kits. If you didn't know, Intel's VDIMM requirement for memory used with the i7 CPU/X58 chipset is 1.65v to prevent damage to the i7's internal memory controller. Though the standard voltage for dual channel DDR3 memory modules is 1.5v, voltages for DDR3-2000 modules commonly run 1.9v and higher. This posed a definite challenge to the memory guys… regardless of speed, timing, or overclocking capability, 1.65v is it!; no extra voltage to add stability to that high speed or those tight timings.

http://www.ocia.net/reviews/oczblade1600/page1.shtml