What I want is the most quietest cooler that does great in also keeping the CPU cool. I have an ASUS z87M-Plus with an i5-4670k and an HAF 912 Mid Tower case. I have been recommended to get the Noctua D14 series the most out any other coolers... and have heard Closed Loop water coolers are a bit excessive and sometimes more noisy due to the pump then decent heatsink/fan coolers. But Im confused between the D14 vs the D15? Is the D15 newer and better? Are there other ones that are just as good that people havent recommended?