A pair of vipers in push pull works very well, blowing inwards. If you get a gelid or akasa pwm splitter cable you can plug them both into the 4pin cpu motherboard header and have the motherboard bios control them. They usually stay under 800rpm, and are very quiet. Even when gaming they shouldn't go over 1200rpm, and only when stress testing with prime or intel burntest have I seen them go to 1900rpm. Loud but more the sound of air whoosing. The Vipers also have some of the highest static pressure around of any fan (bar maybe some deltas) so are well suited towards the H50. Even the Apache Blacks are very good. Same fan, but in black and top out around 1350-1400rpm, so quieter.


