Definiteive explanation / recommendation requested for 3 or 4 pin fans.

ginjaninja

ginjaninja

ginjaninja

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http://dlcdnet.asus.com/pub/ASUS/mb/LGA2011/X99-A/e9736_x99-a_ug_v2.pdf

i plan to buy this board.
The manual seems to suggest that it can use both 'DC and PWM to control fans'.
I have a cosmos II case which has 5, 3 pin case fans as standard (swapable for other fans if recommended), with a '4 channel fan speed control'

I would like quiet when the pc is not stressed..but capable of good cooling when required...so i assume i want variable fan speed.
this asus seems to have 4 pin chasis fan headers

Questions
  1. Does 4pin=pwm and pwm=4pin, when talking about fans?
  2. Is the five pin fan_ext for the optional fan extension board in deluxe manual? are fan_ext boards generic or do you have to buy the manufactuer's?
  3. how different are 3pin on a cases fan controller , 3pin on a motherboard that controls via dc.and 4pin pwm on the motherboard. in terms of ability to minimise noise/cooling until required?
  4. In an ideal world, if you had complete choice over equipment, if your preferred fan came with both 4pin/pwm or 3pin option, which would be preferred?
  5. I dont want to manually change my fan speed i want the system to know when to increase fan speed automatically, does it suffice that the board is able to control 3 pin fans with dc...or is this a 'poor man's solution' and i should really swap to 4 pin case fans to ensure the closest/most complete match through the widest speed spectrum against temperature - minimising noise until required?
  6. Do modern motherboards have 4 pin fan headers as standard now, or is it manufacturer specific?.
  7. Can 3pin fans fit on 4 pin headers?
  8. If 3pin fans can't fit onto 4pin headers and 4 pin headers is now standard, how do i connect my case fans? or am i recommended to replace my case fans with 4pin fans?
  9. Fan specs for new fans on OCers often dont say whether the fan is 3 or 4 pins. isnt that important?
  10. If my case has 5 fans of 3 pins. but the motherboard only has 5 fan headers (two of which are for cpu not case fans, and one is for 5 pins fan_ext), what am i expected to buy to attach all the case fans?
  11. Are case fans not expected/recommended to be variable?
  12. If the case has a controller, is it expected that the cases fan would completely bypass the motherboard. Do the cases fan plug into the cases fan controller direct. Does the cases fan controller act like the 'control by dc option' of the motherboard but without the automatic and granular control on temperature.
  13. Do I need to buy temperature sensors if I want the motherboard to control fan speed automatically against temperature..or do the motherboards use only the cpu temp to control fans.
  14. do I have to buy asus sensor for asus board..where can I buy asus sensor from?

thanks for advice.
 
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A bit of reading suggest answers

1. yes they are equivalent.
3,4,5 if you want speed to vary automatically with temperature then pwm fan is ideal as its designed to change speed and will have a wider more granular response to the speed control.
7+8...3 pins fit onto 4 pin headers, there is a physical key/protrusion on the 4 pin header to line up to the 3 pin fan.
10...Doesnt seem you can buy the asus fan-ext in the uk...the deluxe product comes with one
12...Seems this is the case,
13...seems the motherboard has sensors on chipset, cpu, external thermistor with which to build the fan profile.
14..well you can't buy an asus temp sensor in the uk..the deluxe product comes with one. presumably the asus is calibrated for asus and not interchangeable?

anymore for anymore.

In the absence of any advice, will test with dc control and cosmos ii controller and see if there is satisfactory 24/7 configuration which is silent at low enough temperature and yet cools adequately when the load kicks in.
 
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Very good questions :) I'm afraid I can't answer them but I'm very interested in what others have to say as it's a rather confusing area it seems.
 
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