Depends on the motherboard, more than the processor, right?
I haven't seen any dual-channel RAM boards for a i7 920 or higher, but I could be wrong.
there are some i7 cpus that you can use dual channel DDR3 ram with, those are the socket 1156 cpus. the i7 920 is a socket 1366 cpu which requires you to use triple channel DDR3 memory.
You can use DDR3 in single channel, or dual channel mode. You don't have to use three sticks. However, given that the memory controller is built into the latest Intel CPU's the 1366, and 1156 motherboards require that you use DDR3.