at what point do you need liquid cooling?

I'm in the process of purchasing a new PC.  I'm trying to decide between the processors i-7 4790, i-7 4790K, and i-7 4790s.  I plan to use the Asus Sabertooth Mark I mobo with 16G or perhaps 24G of RAM and a decent graphics card.  I'm not a gamer, but I need a high-end machine because I use voice recognition software and a high-resolution monitor.  I have no interest in overclocking.  I am looking for a reliable and stable computer.  My question is do I have to use liquid cooling for all three processors, or can I get away with fans for the lower power i7-4790s version. 

thanks,

Oodi