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LOTS of questions case fans and motherboard fan headers

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March 19, 2012 4:54:57 PM

Sup all. I just got finished building my new PC after about two months of frustration, and I am trying to learn as much as I can about different parts of the connections and such so I may build another one day. I have managed to find a really good website that explains all the different types of power supply cables, with pictures, with what they do, and extremely briefly, without going into a whole rant.

Now I've been trying to learn more about fans and their connectors, both so I can tell that I am getting the proper type of control that I want, for educational purposes, and so I make sure I'm not plugging fans into places they do not belong. So first, here is what I believe is right, please check it over to make sure.

Fan connectors may plug into the PSU directly via a perephrial (sp?) cable (also called a molex cable). The fan will always run full speed this way, but generate a lot of noise depending on the fan's Dba.

If plugged into the motherboard, there are three types of headers on the mobo I can connect them to....

2 pin connections. These just power the fans. I can plug in a 3 pin or 4 pin fans into these, but the fan will always spin at full speed, generating the most noise, and the third and fourth pins will not control fan speeds.

3 pin connections. These power the fans and provide a "sense", pin for the third pin. This "sense" controls the fan speed via changing the voltage of the fan when the temperature of the CPU changes. 4 pin fans can be plugged into these, but can't take advantage of PWM (but can take advantage of the "sense"), and two pin fans will work just like if plugged into a 2 pin connector

4 pin connections. These power fans, provide "sense", and PWM. 3 pin and 2 pin connectors can be plugged into them, and work how they should. PWM is supposed to be superior to "sense" when controlling fan speed somehow?

The types of fan connectors on the motherboard are CPU, PWR, and CHASIS. The CPU and CHASIS have connections that work like the above described, but the PWR one doesn't power the Power Supply's fan, but monitors it to warn the user if it stops working (and can only be found as a 3 pin connector).

The black wire is for ground, the yellow for +12v, and the third and fourth wire vary in color but control the sense and PWM.

Is this all correct? Kinda a little overwhelming for a n00b such as myself :lol:  .

The other thing I need to know is to make sure my fans are ok and functioning in the way I want. I'm trying to keep fans so quiet I can hear a pin drop, but still provide adaquete cooling for my case.

The case in question is a CoolerMaster HAF 932 advanced. It has a 230 mm fan on the top, side, and front, as well as a 140mm fan on the back.

The motherboard I am plugging all these case fans into is an ASUS P8Z68V PRO/GEN3 motherboard.

Now the mobo has the following connectors for fans, CPU,CPU_OPT,CHA1,CHA2,PWR1,and PWR2. One of the CHA connectors has 4 pins, the other 3 and I believe both CPU fans are 4 pin headers. However, PWM is not listed on the 4 pin CHA connector in the manual, it is listed as +5volts (the heck?). Now, since my case has 4 fans, and I only have two specific connections for case fans, I connected the fans like so...

Top: PWR1
Side: CHA2 (4 pin one)
Rear: PWR2
Front: CHA1 (3 pin one)
CPU: CPU (surprise!)

Is this setup ok? I do have a side panel window, so I can look in, and all the fans seem to be spinning just fine. When I open the BIOS, I can see the PWR1, one of the CHA (not at my computer right now, will update with which one when at home), and both the CPU and CPU_OPT. I have nothing connected to CPU_OPT, so I get an N/A there, but for the rest I get between 300-600 RPM, while CPU temp is at 18-21 Celsius. One of my fans is not being monitored by the BIOS I guess, since I can only see 4 of the 5 fans? What I want to make sure of is they will be controlled by the mobo to spin at high speeds when necessary, and run at low speeds when idle. I also want to make sure my PC isn't going to blow up from connecting two of the fans into the PWR headers. Maybe the one CHA fan that is not being monitored should be plugged into the CPU_OPT instead, or would that be a bad idea?

So yeah, like I said lots of questions :lol:  . Hopefully I organized it well enough.

EDIT: The fans monitored in the BIOS are CHA1, CHA2, PWR1, CPU, and CPU_OPT.


a b B Homebuilt system
a c 151 V Motherboard
March 19, 2012 5:29:28 PM

This is a quote from another forum PCmech.com by "GLC" (forum administrator) dated 9/22/2011
"Do not connect a case fan to the PWR_FAN connector. It is only used for monitoring (NOT powering) the internal power supply fan *IF* the power supply has a lead specifically for that which will connect directly to that connector. Most power supplies do NOT."
I have no personal experience with that function
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March 21, 2012 5:53:22 AM

Anyone?
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March 22, 2012 8:13:18 PM

Hi, sorry for hijacking your thread. It'll be my first time building as well, can you show me the website you're using that you mentioned in the opening post?
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