A silly question about new case fans

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Jun 23, 2014
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Hello. I'm trying to build a computer, i'm going to order some parts and I was thinking about my old case. It has two 120mm fans and I think i can use the front one. I was also considerint to order a cheap one from amazon.

The case I have in mind its the Phanteks P400 or the Phanteks enthoo pro M. Both of these cases has filters on the top, the front and the downside part of the case, so I thought to have one of those "positive airflows" amd try to get inthaes from the top and the front (It should be easy, I guess, its just looking at the fan, right?)

Anyway, the P400 comes with a 120 on the front and 120 on the back. I thought I can put 2x120 on the front and 1x120 on the top of the case (or 3x120 in the front case if thats better) but I have some silly questions I don't really know:

The mobo comes with 3x chasis fans with 4 pin.

1) What happens if the fans has 3 pins? becase i think the cheapest one has 3 pin connectors. Do they work at maxicum capacity? how negative is that?

2) what happens if the cables are too short? Should I attach them to the molex connector of the PSU? would they work at maxicum capacity, right?

3) its a good idea if I use one of those fans as CPU optional fan? A 212x with two fans its something useful?

4) What if I buy a 4 pin fan but its too short? its worth it to buy a 4 pin fan? I just saw 20 euros fans and thats too much, I just want a nice airflow

Thanks al ot
 
Solution
1: You can run a 3 pin fan off a 4 pin header, the fourth pin is for an automatic control signal called 'PWM' that allows its speed to be controlled according to temperature (usually of the CPU). If you look closely at a 4 pin motherboard header you'll see a little plastic tab offset slightly to one side, this locks into a recess in either the 4 or 3 pin connector on the fan lead, so you can only put it on correctly .

2: plenty of computer stores sell extension cables get ones to suit how you'll use the fans-4 pin if you will use the PWM feature (not really useful for a case fan) or 3 pin for manually controlled fans (speed is controlled by setting it in the system BIOS).

3: For a non overclocked CPU, a Hyper 212x with a single fan is...
1: You can run a 3 pin fan off a 4 pin header, the fourth pin is for an automatic control signal called 'PWM' that allows its speed to be controlled according to temperature (usually of the CPU). If you look closely at a 4 pin motherboard header you'll see a little plastic tab offset slightly to one side, this locks into a recess in either the 4 or 3 pin connector on the fan lead, so you can only put it on correctly .

2: plenty of computer stores sell extension cables get ones to suit how you'll use the fans-4 pin if you will use the PWM feature (not really useful for a case fan) or 3 pin for manually controlled fans (speed is controlled by setting it in the system BIOS).

3: For a non overclocked CPU, a Hyper 212x with a single fan is plenty good enough but you can use a pair of PWM fans and connect them together through a 'Y' splitter to a single motherboard CPU header: https://www.bing.com/images/search?q=pwm+%27y%27+splitter&view=detailv2&qpvt=pwm+%27y%27+splitter&id=D7147C7D944A09EE929665CC3B03896C9CE013D0&selectedIndex=19&ccid=dZTYK9Fs&simid=608000231607174023&thid=OIP.M7594d82bd16c86496fe06dd1267867deo0&ajaxhist=0
The top part plugs into the motherboard CPU header, the others plug into the fans. Use a matched pair, mixing fans on one header will give unsatisfactory results.

4: Only use the more expensive 4 pin fans if they're needed, for case fans 3 pin ones are just as good.

Most seem to agree: Front and bottom fans for intake (in), top and rear for exhaust (out), and if you mix fans, put the strongest as intake. Even for a high calibre system 4 case fans should be plenty.
 
Solution