i was just wondering iwhat would happen if i was to reverse the polarity of my cpu fan? ie. suck instead of blow. this is because i have a relatively large heatsync and was hoping to put two 60mm fans on each end sucking out the air whilst the one 80mm fan on top is blowing air in would this aid my cooling? i thought about the pressures and thereticaly i think the air pressure would be up by a considerable ammount. what do you guys think.
This might be just a thought, but why not just pole them correctly and attach them to your HSF on the inflow side instead of trying to reverse the polarity? Also, if you want to use a 60mm on the side, you might want to enclose the top of the heat sink and only put 1 fan on one side kinda like Alpha does? If you put 2 fans (one on eash side) you'll be left with a "dead zone" right above the cpu die, thus defeating the purpose. Using 1 fan and an enclosed top, the air must flow across the entire surface of all of the fins cooling the unit more efficiently, and with 1/2 the noise. Just a thought... and if memory serves me right, if you plug the + wire to the negitive side and vise versa, the fan will do nothing, but I might be wrong. Silver Talon
It would definately easier to just flip the fan then reverse the polarity. I don't really think it would help that much. You would be sucking the air out, but it won't make your 80mm fan blow air onto it any faster. I think you would end up just sucking air around it and having the two be useless.
You can't reverse the polarity of the fan for two reasons: 1. The fan's motor is driven by a transistor, not by the power supply itself, hence the polarity needs to be correct in order for the transistor to switch on. 2. Even if the fan wasn't brushless (what I just described above, like almost all fans for computers are), look at the blade. They are what create the air movement. The blades act as a scoop, if you will, which grab the air and then force it along the path of the blade, which pushes it downward towards the label on the frame of the fan. If you reverse it, any airflow you do get in the intended direction will be FAR less than normally.
I've had heatsinks that seemed to cool better when air was blown on them and others that seemed to do better with air being sucked away. I'd recommend (like others) simply flipping the fan over and using a program like Motherboard Monitor to see if the airflow direction makes any difference. SharkBait
thanks guys. the idea is mainly to have a system like you have in a normal computer airflow set up eg. intake fan and extractor fan so that the air flows the way i want it rather than just down onto the hsync. as you may notice the air passes onto the heatsync at speed but then slowly escapes. my idea is to extract that hot air as rapidly as i can so that it doesnt linger.
also remember that you probably want the top 80mm fan blowing into the heatsync instead of sucking through it... the reason becuase with it sucking air from the sides and expelling it outwards is that its taking the air from the mosfets and other hot parts around the processor.(hot air)... last time i checked you didnt want hot air being sucked through a heatsync... just fyi and yes, just unscrew the fan and put it on reversed...
Put the fan on the top upside down and then have two small fans on the sides of the heatsink exhausting air from it. That would be the best way to do what you want.
