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Case fan wiring question.

Last response: in Components
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August 4, 2008 10:06:20 PM

Ok, I'm currently building my first computer and I have the NZXT Tempest case, Corsair 750TX, and Asus P5Q-Pro.

My question is, there are six case fans and each has two 4-pin molex connectors(one male/one female) and a 3-pin connector. Now, I'm going to assume I can daisy chain some of these fans together and connect one of them to a power supply 4-pin molex connector like this:

Case Fan1(4-pin)---->Case Fan2(4-pin)---->Case Fan3(4-pin)---->PSU(4-pin) or however many fans I want.

Can I also connect them the same way except use the 3-pin wire on the end of one of the fans to connect to the motherboard chassis fan header to control lets say three or four fans? The motherboard states it can support cooling fans of 350mA~2000mA at +12V each or a total of 1A~6A(72W max) since there are 3 chassis fan headers.

I don't know how much power these fans pull so I don't know how many would be safe to connect to the motherboard if what I talked about up there is correct. Also, what is the difference between the PWR_FAN header and the CHA_FAN1/CHA_FAN2 header on the motherboard besides from what I've read the PWR_FAN header is for a power supply fan, and can case fans be plugged into this header without problems?
August 4, 2008 10:29:48 PM

The PWR-FAN header is special and should not have normal fans plugged into it. It's just there for the few PS's with matching connectors that plug in so you can monitor the PS fan in the BIOS.

Personally, I wouldn't plug more than 1 case fan in per 3-pin header. If you try to draw too much current, you'll fry a power transistor on the MB, which you can't fix.
August 4, 2008 10:45:12 PM

some fans do plug into the 12v and also the 3 pin and use the 3 as a speed control, but unless it says that on the fan...don't do it :)  also, you shouldn't try to daisy chain 3 pin fans as mondoman said :) 
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August 4, 2008 11:37:26 PM

Thanks for the replies, I just looked at the fans and the two front fans and the side fan draws 12V 0.20A 2.4W each. The rear draws 12V 0.08A 0.96W. The top two 140mm are unknown.

So, to be able to control the fans it would probably be safer to get a fan controller to put in for controlling the fan speed?

In the mean time, can I at least daisy chain a few fans together and connect one of them to the 4-pin molex connector on the power supply without causing any problem? Or should I just connect each fan to an individual 4-pin connector on the power supply which wouldn't be a problem as there are enough of those connectors.

I just want to daisy chain to reduce the amount of wire cables used so I can hide them easier.
August 5, 2008 4:32:54 AM

Daisy-chaning fans on a molex is no problem. I'd try not to go over 6 per chain.
August 5, 2008 8:11:36 AM

I hooked the fans up and booted the computer for the first time. All the fans spun up, and I was greeted with a nice short beep. I was pleasantly surprised that I didn't have any problems and quickly launched into the CMOS settings. Once there, I began to jump for joy. ;) 

Ok, maybe I didn't jump for joy, but I'm happy everything worked. My next step will probably be testing the RAM.
August 5, 2008 6:23:09 PM

Sounds good! If you haven't already, download memtest86+ for basic testing and some Windows-based stress tester like Orthos or other PRIME95-derived program.
August 5, 2008 8:27:43 PM

You can also wire strip them down and splice into one molex for a cleaner look. Just use some shrink wrap (or just electrical tape if you are lazy) and you will be set. Case fans pull a very small load and running them all to 1 molex won't be a problem; like the others, I don't suggest running them to 3-pins.
!