Hi.
I'm building my first PC system for years and I am seriously out of touch

It's taken me a few months to read reviews and I'm pretty much settling on all of the other components now apart from RAM (and case/chassis but that's for another thread!).
What's really confusing me is the various voltages and frequency's available.
The rest of the system is going to be:
- i7 3770k IvyBridge
- Noctua NH-D14 CPU Cooler
- Asus P8Z77 Pro or Premium board with Thunderbolt
- Corsair 600T case with sound dampening added
- Coolermaster 620w Silent Pro Modular PSU
I'm not adding a dedicated GPU right now as mainly using the PC for encoding.
I will be overclocking the CPU but not at the expense of noise, so somewhere around 4.2 - 4.4 sounds sensible.
I'd like to add 16GB of RAM and the Noctua website guides me towards Corsair XMS3 or Vengence Low Profile RAM to ensure it fits below the CPU cooler. But when looking on the Corsair site I see there are different voltages, latency and speed to choose from and now I am confused! I wasn't intending overclocking the RAM (is there any point when encoding?), so what is the best choice? Is there any point going over 1600Mhz for example as I understood that is the max bus speed of the CPU?? And what voltage do I need?
Thanks