I7-2600k and which rpm for case cooling

[Guest]

there are 2 fans in front, 1 on side for GPU's, 1 in back, 2 up top. i have 2 GTX 460s in SLI and an i7-2600k. what RPM fans and where? also whats the best CPU cooler for around $50. dont plan on overclocking too much.

 

[Guest]

thinking about a cooler master hyper n 520 because sandybridge doesnt run as hot as other CPUs