Standard can be silent, depending on what kinda fans ur using that is... you could opt for the Artic F12 or the Bitfenix Spectre Pros for good noise/performance ratios, just get the 3-pin version will do if its for intake and exhaust

PWM means Pulse-width modulation and it enables speed control based on the temperature sensor thats' built in to the motherboard.. its a 4-pin header for these fans but most mobos will only have one or two of the 4-pin headers while the rest will be 3-pins