if you are building a performance and a gaming pc, please don't expect it to be quite.
if you'll be using a sli both the card when on full load will make much a noise.
to cool the system to the best use the following
all fans should be 120MM
1 intake fan where hdd are placed.
1 outlet fan at the back panel
1 outlet fan at the top of the cabinet from the inside if supported.
that will cool the system down significantly