I guess it depends on the batch of the chips. My friend has his at 4.2 GHZ with out changing the voltage and it's stable. I have some at work that vary between 3.9 and 4.5 without changing voltage, but these are in an air conditioned lab room (Like 5 degrees Celsius in there). So it really depends, but I would say 4.2 ghz is average in my experience. My experience with LGA1155 is pretty small though, most of my stuff uses LGA2011.
The prefilled liquid cooling is more of a noise reduction option and not so much performance. I have one and it cools just as well as an air one, but it's much quieter.
For streaming, I don't think you need more than stock speeds. If your upload speed is really good, you do less compression so less CPU usage. So the CPU usage will vary by your upload speed. If you can upload at like 2~3mpbs, you shouldn't need to worry too much about your CPU (This is based on the assumption that you will stream at 720p).
Last edited by Shugi; 11-18-2012 at 09:49 AM.