Since newer CPUs have on-chip memory controllers the need for extra VDIMM is far less. The newer Intel cores are limited to 1.65v which is a long way down from the original 1.9v required for C2D.
Technically C2D doesnt require 1.9 V, Most C2D's are paired with DDR2 and the official spec voltage for DDR2 is 1.8V, The official spec voltage for DDR3 is 1.575V(max).
Thing is when overclocking a lot of memory makers spec overvolted parts, so 1.8V DDR2 often ended up 2.1V etc.
Its not really that the i7's are voltage limited to 1.65V either, more a fact that pushing more than 1.65v into the i7's memory controller will fry it pretty fast as its on the die, and made with the same 45nm process as the rest of the CPU. So the ram guys have got less voltage headroom to get good overclocks from stock parts, and have had to resort to using higher than jedec spec parts to get higher clock speeds and tigher timings.
The advantages of the low voltage ram are, A) uses less voltage and power to achieve the same timings, B) slightly less temperature due to A. C) Compatible with i7 processors without risking damage to the cpu should you upgrade in the future.
Standard "Low voltage" memory should work just fine in AMD rigs, but overvolted ram is bad for i7's. Thats about it really. The AMD memory controller is more robust than the i7 one.. its design is more tolerant of voltage than i7.
