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Two fans.... one header?

Cyber Akuma

Cyber Akuma

Gawd
Joined
Jan 3, 2009
Messages
663
My motherboard is an Asus P8Z77-V Deluxe, and my case is a Cooler Master HAF X. Not counting the CPU fans, my motherboard supports headers for an additional 4 case fans.

The HAF X lets you put in several optional fans, I decided to use some of these for better airflow due to the large amount of drives that will be in the system.

Two of them pretty much serve the exact same purpose, they are exhaust fans that push air out the top of the case. And while I do have a 4-pin header for one of them, I don't have one for the second. I know there are cables out there that let you connect two 3 or 4 pin fans to a single header, but I know these these have problems.

First of all, ones that have all pins for both fans tend to confuse the motherboard by feeding it two RPM monitoring signals at once (Again, since they both serve the same purpose and are in the same location, just motoring the RPM of one of them and adjusting both accordingly at the same time is good enough). So I am guessing I need to keep an eye out for a cable that has pin 3 missing from one of the two fans it connects to right?

Second, would the motherboard be able to supply enough power? They are two 200mm fans, and both have leds as well. I couldn't find information on how much power the fan headers on my motherboard supply, or how much the fans use (Cooler Master Megaflow 200).

I know this is kinda a long shot but, does anybody have any idea if I would be able to connect two of these fans to a single header on my motherboard?
 
No problem whatsoever with 2 fans. I would guess you could probably pull over 1A from a mobo header, so 2 200mm fans shouldn' t be any problems at all :)
 
i'm curious about this a well.
I'm attempting to do something similar with my sabertooth 990fx r2 MB. In my manual, it only gives specs on the cpu & opt cpu 4pin header which i believe are a couple of watt/1amp. That's more than enough to run 2 fans in most cases. The other 'CHA fan' headers have no specs in manual.
I'll be hooking up twin 80mm & twin 92mm fans to 2 seperate 4pin 'CHA' headers on my sabertooth mb. They don't require much power, maybe 0.1 to 0.2 amps each.
 
I'm using a total of 9 120mm case fans and 1 120mm CPU Cooler fan, all running off my MoBo headers. I am using Arctic Cooling PWN fans for the case, and they have the daisy-chain connectors built in to the cabling....no problems with power draw, even at full RPM.
 
I'm personally a big fan of fan controllers. Nothing like being able to manually control all of your fans just how you like 'em. You can find a nice one for ~$20-30 USD.
 
What problems are you talking about with PWM splitters? They will only have 4 wires going to one of the splitter ends, all the others will have 3 wires (rpm sensor one will be missing) and so the mobo will only get the RPM from one fan.

As for will it be able to power them off of one header depends on the mobo header and the fans power draw. It will say on the back of the fan how many amps it pulls and it will say in the manual for the mobo how many amps can be pulled through a header, most being at least 1A.
 
I'm running 4 80mm fans off one header with no problems, but I tested & measured first. Set up a bench to run the fans off a spare PSU and measured the current draw. Each fan pulled .1A (Enermax Marathon 80mm) at full tilt, and with a cheap PCI slot fan controller, I couldn't get more than a .5A draw out of the setup, which I felt very comfortable with.

If I had done the testing and it was around 1A, I would have pushed the testing further (holding some fans back, increase heat w/hairdryer, any idea that could cause a larger current draw) - and if it was over 1A, I wouldn't do it unless the mobo was spec'd for it. I've seen some say .5A per header, but most newer boards I've had say 1A.

I would definitely measure the 200mm LED fans. Hate to kill a mobo just for the sake of cleaner wiring & software fan control.

Artic's daisy chain PWM fans are great too.
 
How would one measure fans? I have no idea how to go about doing that.

Everyone is telling me that Asus is great at chronicling what ports supply what power in their manuals but I don't see it.
 
To measure current, you will need a multimeter and a molex fan adapter you're willing to cut apart. You just have to cut one of the wires on the adapter, connect each multimeter lead to one of the cut ends, and fire it all up. The meter will then tell you how much current is flowing through it.

In my Asus manuals, I see the CPU header is spec'd but the chassis fan header are not. I can't remember where I tracked down the specs for those.
 
Cyber Akuma said:
How would one measure fans? I have no idea how to go about doing that.

Everyone is telling me that Asus is great at chronicling what ports supply what power in their manuals but I don't see it.
Click to expand...

You don't need to mesure the fans, the sticker on the back has the amp draw listed.

5 seconds on google, 30 sec on asus website, 1min to DL and look at the manual and:

0irpp.jpg
 
The fans will draw the most current at startup when the acceleration of the motor is the highest. Once at steady state the current draw will go way down. But being able to measure that half second draw on a digital multimeter will be about impossible.
 
Sunbeam used to make a multiple fan plug in device which got its power from a single molex connector. I am sure you can still find them.
 
Jarod888 said:
Sunbeam used to make a multiple fan plug in device which got its power from a single molex connector. I am sure you can still find them.
Click to expand...

Many places make PWM cables like this, here is one example.
 
BlueFireIce said:
You don't need to mesure the fans, the sticker on the back has the amp draw listed.

5 seconds on google, 30 sec on asus website, 1min to DL and look at the manual and:
Click to expand...

Yeah, my manual says that too, but that is specifically referring only to the main CPU fan header.

Although if its true that the headers are 1A, the fans are 0.16 with a max of 0.28, so it should be more than enough to handle two of them.
 
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