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Kodan

New fans on Crosshair 6 Hero break fan control across all fan headers

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Posted · Original PosterOP

Hi there!

I have been running my system with the following fan configuration without any issues across multiple BIOS revisions on a Crosshair 6 Hero:

1x PWM extension going from CPU_FAN to an Aquacomputer Splitty9 going to 5 Corsair ML Pro 140mm fans

1x PWM extension going from CPU_OPT to an Aquacomputer Splitty9 going to 3 Corsair ML Pro 140mm fans

3 Noctua NF-F12s bundled via the included Y-splitters going to CHA_FAN2

 

I recently swapped the radiator fans for 4 NF-A20 fans to save myself some wiring and to improve noise, but those new fans do not show up in UEFI at all. RPM is reported as N/A.

My new fan setup is:

1x PWM extension going from CHA_FAN2 to an Aquacomputer Splitty9 going to 4 Noctua NF-A20 PWM

3 Noctua NF-F12s bundled via the included Y-splitters going to CPU_FAN

 

According to the manual, all headers were and currently are capable of driving the fans I hooked up to them. I had the Noctua fans split across both Splitty9s and hooked up the CPU_FAN and CPU_OPT (2 per header, essentially) with no difference in behaviour.

 

When in UEFI I can now see CPU_FAN reporting RPM correctly, but I can not make a fan curve for it because whenever I select that header to customize fan curves, it jumps to N/A and will remain there until reboot. CHA_FAN2 that I want to use for the external radiator is also on N/A both in AISuite and in UEFI. When I switch sources from which to pick temperatures from I can hear the fans changing speed, but I can't see that in the software as there is no RPM reported, and I can't make a fan curve for this header, either.

 

I have updated to version 7901 using the EZ flash feature, but no changes. I currently have no control over either set of fan headers, and the ones hooked up to CPU_FAN are stuck on 100%.

 

When I switch all fan headers to DC mode fan control suddenly works, but I only get a range from 60-100% in the software when making fan curves, even for the CPU fan headers.

 

Any help would be appreciated.

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I got totally lost trying to follow your setup change went from 3,3 and 5 to 3 and 4. I don’t know how this works.  Apparently there is an external radiator of unknown size.  So I’m going to ignore the fan layout.

 

I got 1 idea which might not even apply:

you may have some pwm wires with too many friends.  You can’t Y split a pwm wire and have it work right.  They only want to talk to 1 fan and all the other fans on that header are slaves.  The reported rpm is only ever for that one fan. The others are just along for the ride.  In the olden days from whence I come, a Y splitter would have a 4 pin at the base and on one of the branches, but the other(s) will only be 3 pin.  If you’ve got 4 pin fans you have to let one pin hang off the side for any slave fan. If the pwm gets Y split everything goes wacky.  
 

 


Life is like a bowl of chocolates: there are all these little crinkly paper cups everywhere.

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Posted · Original PosterOP
4 minutes ago, Bombastinator said:

I got totally lost trying to follow your setup change went from 3,3 and 5 to 3 and 4. I don’t know how this works.  Apparently there is an external radiator of unknown size.  So I’m going to ignore the fan layout.

 

I got 1 idea which might not even apply:

you may have some pwm wires with too many friends.  You can’t Y split a pwm wire and have it work right.  They only want to talk to 1 fan and all the other fans on that header are slaves.  The reported rpm is only ever for that one fan. The others are just along for the ride.  In the olden days from whence I come, a Y splitter would have a 4 pin at the base and on one of the branches, but the other(s) will only be 3 pin.  If you’ve got 4 pin fans you have to let one pin hang off the side for any slave fan. If the pwm gets Y split everything goes wacky.  
 

 

Oh I am sorry. Maybe I can help with a couple pictures.

This was the setup before the change (when everything worked):

A69mVQA.jpg

 

There are 9 fans on here going to 2 splitters. 5 go to the upper splitter, 4 to the lower one (where that bundle of cables is in the bottom right. It's 2 of these splitters:

splitty_2_600x600.jpg

They have a PWM cable as input and copy that signal to the other headers. With the 9 corsair fans, that worked.

The case fans are 3 Noctua NF-F12 and they were hooked up to my CHA_FAN2 PWM header. There are 3 of them in the top of the case and they are linked together using Y-splitter cables that all end in a single PWM fan header going to the motherboard:

 

DENbJU3.jpg

 

With this setup everything could be controlled using either the AISuite Software of the MB, or through whatever I set in UEFI. It worked. Always.

 

Now for the changes.

This is the setup of the radiator now:

ajsweGC.jpg

 

9 Corsair fans are gone, 4 Noctua fans are used instead. Instead of having half of them go to one splitter and half of them to the other and having two wires run to the motherboard, there is now just one. I hooked it up and it didn't read the RPMs of them at all. No RPM control works whatsoever. With the Corsair fans this was not an issue. They were hooked up to the same fan headers and it worked.

 

I would like to have the option to deactive the fans with certain water temperatures, so I opted to hook the radiator up to a fan header, since you could run them off the water temp sensor reading - this is not possible for the CPU fan header. That header is now used for the Noctua fans in the top of the case.

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