I am doing research on cooling fans to build a gaming PC early next year. I have a question regarding the rpm for the cooling fans. I have looked at several 120 mm cooling fans. I saw two types of fans built by Corsair and will use them as an example:
Well for your first question I choose higher rpm fans because they produce more CFM and better airflow in the case but if noise is a factor then go for the quiet edition. As you can see both fans have a dba measurement which is basically how loud they are. In addition, the higher rpm fan will use a bit more electricity than the lower rpm fan but its barely noticeable maybe 1-2 watts more? Fans typically use about 2-7 watts, 7 means the extreme high performance fans like those delta fans that spin at something like 3000-4000 rpm. To calculate the exact amount multiply the amps and voltage of the fans to get the maximum wattage it uses.
RPM alone does not a good fan make. Large fans move more air than small fans all else being equal. And do it with far less noise. As mentioned above, look for the CFM rating over fan speed. You're not after fast air flow, just lots of air flow.