I'm partial to Noiseblocker eLoops. The 140mm version that I own are almost silent at full blast. Their PWM 120mm version, three of which I run on a 360mm radiator, are quite a bit louder at full blast - but much, much better than any stock fan with similar CFM. Both the 140 and 120mm versions, when set as intake fans, tend to vibrate and buzz. That doesn't happen when they are set as exhaust fans.
 
That said, you should still have a warranty on your Hybrid. Contact EVGA and see about getting a replacement - www.evga.com/about/contactus/ 

From their website (yeah, they're based in Germany) - http://www.blacknoise.com/datas/downloads/datasheets/TData_eloop120_122012_de.pdf 

one thing to know is what given CFM  is at what  RPM  
 
say the stock fan is a  70 cfm at 2000 rpm  and you replace that with a fan that just  30 cfm at 2000 rpm ??    so the heat transfer away from the radiator may not be efficient to properly cool  at a full load/heat use   
 
so you really cant use any fan you want as said above    you don't push enugh air throught he radiator  ? well its not going to cool the liquid  as well  . like your car the fan fails your engine  starts to run hot  ????  
 
good luck 
 

i use corsair fans (red leds) for my 980 ti hybrids they keep my cards around 40-45c

atanri01
gamer nexus has some pretty cool ideas

Yeah, I checked out Steve's site.  I'm a big fan of his youtube channel.  So what I ended up doing is putting a Noctua NF-F12 on that 980 ti and put the card in my wife's PC.  She only had 1 extra fan header so ended up doing push configuration.  I turned around and got a 1080 ti Hybrid SC2 for my rig and put 2 Cooler Master PWM high static pressure fans in push & pull on my new card.  most games in 4k i get 45 to 50 C.