Fan PWM, straight or through a shield

Hi folks,

I am planning some kind of automated ventilation system. I have bought a 12V 4A Delta server fan which I want to drive with Arduino and a ATX PSU. I was unsure that I could use the fans own PWM-line, so I bought also this mean looking 43A BTS7960B motor shield. The fan has four wires and I read that I actually can use the original PWM-line with arduino to slow down the motor.

So money is not the issue now, but rather more which is better for this purpose?

Try the provided PWM line - if it works you are sorted.

Thank you for your answer. I am bit of a "not-so-easy-customer", so I still would hope little more on this topic. I need very good reliability for my system. I want it to be built to last for years of continous running. From this point of view is there any known weaknesses in either one of them. I basicly meant to ask which one should last longer, at least in theory? Or is it really just the same which one I choose to go along with?

I do not need to reverse the fan, or anything like that. Just want to adjust fan speed according to ambient temperature. With 230V fans I have heard that people recommend using lower voltages rather than other types of dimmers. Lower voltages makes least extra sound while other dimmers make those 230V fans to buzz. Would lower voltages be better for 12V fan than PWM for dimming? Why or why not?

If somebody wants to help me out with this, I hope that you understand that I am quite new to electronics and will be happy with quite simplified answer as long as it seems logical.