What do you mean "clicks correctly"?  They're not supposed to click when coming on - if they do that, it's usually a sign that there's not enough power on the 12V rail.  I had an 850 that couldn't run two cubes at once without clicking and resetting.  I switched to a better 750 that could run two at once and no clicking or resetting.  I've had seven different cubes, all ran at high clock, and none clicked unless power was not up to snuff.