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Question How many fans can I connect to this mobo?

Osama Nawaz

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May 5, 2015
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I have an asus b85m-e. It has two chasis fan headers.

how many fans can i connect to each with a splitter? I saw the manual and it said the fan headers had +5V.

The fans I am using are 3 masterfan mf120L red. I want get two more fans, two 140mm fans for the front.
Can I connect these to the motherboard with a splitter or do I need a fan hub?
 
Yes you are okay as it says 2amp for the header and the fans should be a lot less at a max of around 0.36A so 3 onto one header should be fine...and just double checked your fan rating which is a meagre 0.16a for the masterfan mf120L red so you are more than okay...
 
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Osama Nawaz

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One fan header can handle 3 x 120mm fans or 2 x 140mm fans...Use a splitter and you should be fine..Also just checking your manual to get an accurate figure..
Ok nice to know

I read the manual but all i see is that it says that the fan headers are +5V
not sure what this means,
 

Osama Nawaz

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Yes you are okay as it says 2amp for the header and the fans should be a lot less at a max of around 0.36A so 3 onto one header should be fine...and just double checked your fan rating which is a meagre 0.16a for the masterfan mf120L red so you are more than okay...
Thanks

Can you show me where it says that?
The place where i saw it only said it about the cpu fan header
 

Osama Nawaz

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These aren't RGB fans are they with separate rgb connector? Just normal fans?
normal fans with 3 pin connectors
Fans are 12v. Fan headers are 12v. Rgb/argb is either 12v or 5v. Don't confuse the two different headers. Lighting and fan operation are 2 entirely seperate things, even if the lights are glued onto a fan.
it says they are 5V on the manual though, the fan headers i mean.
 

Osama Nawaz

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Yep I have your motherboard manual open as well as the Masterfan manual open...Will do some more checking and get back to you and hopefully some else will also jump in as we have some really knowledgeable people on here...
thanks appreciate it

what i understand from what karad was saying is that fan headers are all 12v. the lighting has a separate 12v or 5v on the header.
is that right?
 

Karadjgne

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Gigabyte support replied this when I asked them what 5V PWM fan to use with the EP-45-DS3R:
"The fan header is actually 12v, there is an typo on the user manual.
Any standard system fan should not be an issue with the board"
To answer the question, regarding pwm fans, if using a powered splitter/hub with power supplied by molex/Sata, then you can use upto 10 fans per header, that's the limit of the pwm signal strength.

For use with analog 3pin fans, the header rating is 1.0A (supposedly) but honestly fan usage should not go beyond @ 0.9A. For 0.36A fans, that mean only 2 fans or run an extremely high chance of burning out the supply circuit. 3pin fans cannot be used on powered splitters/hubs, and expect any speed control, with the exception of a few 3pin control hubs such as the Corsair Commander Pro, or Phanteks versions.
 

Osama Nawaz

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To answer the question, regarding pwm fans, if using a powered splitter/hub with power supplied by molex/Sata, then you can use upto 10 fans per header, that's the limit of the pwm signal strength.

For use with analog 3pin fans, the header rating is 1.0A (supposedly) but honestly fan usage should not go beyond @ 0.9A. For 0.36A fans, that mean only 2 fans or run an extremely high chance of burning out the supply circuit. 3pin fans cannot be used on powered splitters/hubs, and expect any speed control, with the exception of a few 3pin control hubs such as the Corsair Commander Pro, or Phanteks versions.
where is that quote from? cause im using an asus mobo. is it about the same motherboard but diff brand?

i think these fans are 0.16A. thats their listed safety current which i think means their max. so i can use around 5 of these on one header? they can be controlled on a splitter directly connected to a fan header right? no molex or anything on it.
 

Karadjgne

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Asus has never used 5v for a fan header that I ever heard of, fans are 12v whether pwm or analog.

No matter what manualslib says, it's a typo, there were no fan headers that supported over 1A on any motherboard I've ever seen, especially the older variety, until you got into mobo's designed for water cooling setups, which may or may not have a dedicated aio/pump header, and those are only found on the most expensive boards since no one I've ever heard of put a full custom loop on a B85 platform, not when most loops average starting price is @ $500 ish.

Take it that at most you have 12w on a cpu/sys header, that's 1A at 12v.
 
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Osama Nawaz

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Asus has never used 5v for a fan header that I ever heard of, fans are 12v whether pwm or analog.

No matter what manualslib says, it's a typo, there were no fan headers that supported over 1A on any motherboard I've ever seen, especially the older variety, until you got into mobo's designed for water cooling setups, which may or may not have a dedicated aio/pump header, and those are only found on the most expensive boards since no one I've ever heard of put a full custom loop on a B85 platform, not when most loops average starting price is @ $500 ish.

Take it that at most you have 12w on a cpu/sys header, that's 1A at 12v.
Ok

Can I assume that my case fan headers are also probably 1A? I know it is atleast 0.32A as one is running two fans right now no problem.
 

Paperdoc

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I think I can explain the 5 V thing.

All the fans run on 12 VDC max. On that mobo (and many others) they use 4-pin fan headers for all fans. Yet this mobo apparently does NOT use the new PWM Mode to control its CHA_FAN headers - it uses the older 3-pin Voltage Control Mode, in which the voltage supplied on Pin #2 is varied to change fan speed. Now, the new 4-pin PWM fans CAN be connected to such a header and work properly - that's part of the backwards compatibility features in their design. But some such fans are happier if they get a constant 5 VDC supplied on the PWM signal line (which is Pin #4) rather than nothing from there. So you see in the mobo manual drawings for the CHA_FAN headers that their Pin #4 is marked as "5V". This has NOTHING to do with fan power supply. It is ONLY to keep a PWM fan happy on this header that is NOT using PWM Mode.
 
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