fan voltage/speed questions

[x509]

Some guys say that you should install fans with more CFM than you really need, so you have some headroom if you cooling needs increase. Then you adjust the fan speeds to meet your needs.

That sounds good (no pun! ) but I'm wondering. Say I really need fans (for a triple radiator) that run at 1000 rpm. And let's say that I going to use Gentle Typhoon fans because a lot of guys recommend them.

OK, now which speed fan should I get?

How low can I set the fan voltage and still get the fan to work?

If the fan is running at say 9.0 V, does that mean that the fan puts out 75% of the rpm and 75% of the cfm? What about static pressure?

Is the fan noise also going to be 75% of the rated dBA (assuming I can believe the manufacturer's specs?)

Thanks for answering these questions.

x509

 

[TaCoSwInDeZ]

Hmm...most fans will start to operate somewhere in the neighborhood of 7volts, after they are spinning ive seen some able to go all the way down to 5 volts without stopping for the higher rpm fans. As for the volts/rpm curve I would seriously doubt that its quite that simple and linear however it could be close I assume. For the fan noise there are alot of variables that come into play such as where its mounted, whats in front of or behind it such as wires, grills, etc. and also how much pressure its having to create to move air through the case. Its pretty much a guessing game alot of times and you just have to try it and see if your satisfied. Just as always in the overclocking world, alot is trial and error and just knowing what will and wont work.