Check out my build. i specifically designed it to be a high performance gaming rig with minimal noise. to do this we have to accept some higher temps than many here would like by running fewer fans at lower speeds.
XSPC EX240 kit + XSPC GTX TITAN/780/780Ti VGA block
i have a 3.4Ghz i5 4670k overclocked to 4.4Ghz and my gtx780 is not overclocked
during gaming the CPU never goes over 57c and the GPU gets to 39c. when idle both chips sit around 28c.
all fans are set to run at 50% power until the CPU hits 65c which allows for very quiet high end gaming while allowing the full cooling power to come online if some very intensive task like video editing is required. i'd say the entire loop cost about $275 and it is much quieter than my old AIO which was starting to keep me up at night. AIO are a great if you don't want to overclock but as soon as you do the fan will have to go near full power to compensate and it gets LOUD. I really think its worth the money.
edit: the case has a lot to do with how quiet the pc runs as well. you can easily find lists of cases that are specifically aimed at noise reduction. the trick is to find the balance between noise and cooling power.Edited by d00bzilla - 3/23/14 at 10:09pm