With a decent CPU cooler, it won't ever reach a temperature that requires the fan to rev up. You'll probably rev up your case fans first when you need it
As for power supply, you'll need something that provides at least 30A on the 12V rail. I've found a 520W Antec PSU
that will do the job, but I'm partial to Seasonic since they routinely get really positive reviews. This one (620W)
should do really nicely, and it's only about $20 more than the Antec one (plus 40A @ 12V is kind of pushing it for a 30A @ 12V requirement)
EDIT: I realized the one I recommended spits out 24A @ 12 per rail (2). This shouldn't be a cause for concern assuming they wired the PCI-Express plugs on separate rails.