The key points about RAM and building an Intel Core i7/5/3 system are:
The memory controller is integrated into the CPU, so Intel recommends using RAM that follows the JEDEC standard spec of 1.5v, up to a max voltage of 1.65v; any higher and you could damage your CPU.
The default memory multiplier is 8 x bclk; default bclk is 133, so the default memory speed is DDR3-1066. You only need faster RAM if you intend on OC'ing. However, do note that most of the time, DDR3-1600 will be priced similarly to DDR3-1066, and the higher speed RAM can downclock to the lower speeds if needed. DDR3-1600 will let you OC an i7 930 to around 4.2Ghz, without needing to OC the RAM.
Lower timings are better, but they do not provide enough of a performance improvement to justify a noticeable price premium -- higher speed yields more noticeable performance gains than lower timings, but typically only if the CPU is OC'd along with the RAM.