CPU OPT fan header question.

[kol12]

I've just installed a two new Corsair AF140's in the top of my Corsair 450D. One had to be plugged into the cpu opt header for the lack of fan headers left.

The fan on the cpu opt header idles at around 1220 rpm where as the fan on the standard fan header idles at around 720 rpm.

Why does the cpu opt header run it at such high rpm on idle? It's already close to max rpm (1500 rpm) I'm thinking that it's obviously because the cpu opt header is not designed to be a normal fan header...

Will this be causing any sort of cooling mismatch? Should I look for an alternative configuration?

 

[Tradesman1]

You have the other fan on a mobo header? If so simply get a splitter and run both upper fans off the mobo header

 

[kol12]

You have the other fan on a mobo header? If so simply get a splitter and run both upper fans off the mobo header

Yes one fan is on a proper fan header and the other is on the cpu opt header. I had a look though my spare PSU cables but couldn't see anything of use.

A splitter sounds like the solution, are both fans then controlled by that fan header?

 

[Karadjgne]

Cpu_opt on most mid-low range boards is usually a non controlled header, it runs straight 12v so is actually good for things like the pump on an aio etc. On the higher range boards it may or may not have some control, so that'll depend on what your software/bios settings are and the addresses it uses.
As said, simplest solution is to use a splitter off the sys_fan header you are using for the other fan, just get the correct type, 3-pin or pwm. A splitter uses 2 wires for one fan and 3 for the other, that being 12v, ground and a tach, so reads the tach for one fan and adjusts the voltage to the header, thereby controlling both. Works the same for pwm, but uses 3 wires and 4 wires, that being 12v, ground, tach and pwm, where the tach is to 1 fan and the pwm signal controls the speeds of both.

 

[kol12]

Cpu_opt on most mid-low range boards is usually a non controlled header, it runs straight 12v so is actually good for things like the pump on an aio etc. On the higher range boards it may or may not have some control, so that'll depend on what your software/bios settings are and the addresses it uses.
As said, simplest solution is to use a splitter off the sys_fan header you are using for the other fan, just get the correct type, 3-pin or pwm. A splitter uses 2 wires for one fan and 3 for the other, that being 12v, ground and a tach, so reads the tach for one fan and adjusts the voltage to the header, thereby controlling both. Works the same for pwm, but uses 3 wires and 4 wires, that being 12v, ground, tach and pwm, where the tach is to 1 fan and the pwm signal controls the speeds of both.

Cheers. I can't see any sort of control for the cpu opt header the bios. I had a look through my mobo manual and it doesn't state what the maximum power output on the fan headers are but I would imagine two fans would not be a problem... I'm surprised PSU manufactures don't include Y splitters or Mobo for that matter, maybe I should check my mobo left overs just in case.

I've just discovered that the two extra short adapters that came with the AF140's might be low noise adapters, what are they all about and should I have used them?

 

[Karadjgne]

Most mobo's have a top end of @1Amp per header. Realistically aim for @0.6-0.7Amp at best. Your really good fans only use 0.2Amp, most average @0.3Amp and older, crappy fans can be as much as 0.5Amp. So generally, 2 decent fans at 0.3Amp is all that's recommended for any header safely.

Noise from a fan is entirely relative to the speed at which it spins. A crappy designed fan at max rpm is going to be louder than a premium fan at the same rpm, but the audible volume goes down the same amount as the rpm. Meaning, a good fan at 1200rpm and 30db(A) might be 18db(A) at 900rpm and a crappy fan at 1200rpm and 50 db(A) might be 28 db(A) at 900rpm. So, the fan at 12v will run 1200rpm at its specified noise levels. A LNA is generally a resistor to cut that 12v to 9v, thereby not allowing the fan to see 1200rpm, but only 900rpm, lowering the noise levels. The ULNA is usually 5-7v so cuts the rpm back to 500-700rpm, or about 15 db(A) / 20 db(A) making it an ultra low noise adapter. (these are general numbers for theory purposes, but the theory is correct)

Do you need them? Generally no you don't, unless you want to leave an uncontrolled fan running constantly at low rpm and low noise levels. The Noctua NH-D14 is a good example, two fans, the 140mm running a constant (almost silent) 900rpm, but the 120mm being run by the cpu_fan header being variable from @400rom to 1200rpm depending on temp demand.

 

[Paperdoc]

I recommend you do NOT use those Low Noise Adapters. They are for when you can only connect a fan to a fixed 12 VDC supply and have no way to control the fan speeds. In that case, using a LNA will slow the fan to some lower speed (with less cooling, of course, and less noise).

BUT your better option, as Tradesman1 has suggested, is a fan Y-splitter. What is going on right now is that the CPU_OPT header is being controlled by the temperature measured inside the CPU chip, just like the fan on the CPU_FAN header. But the other fan - the one connected to a mobo SYS_FAN header - is being controlled by a different temperature sensor built into the mobo, and that is what SHOULD be controlling your case ventilation fans.

As a general rule, the circuits on each mobo SYS_FAN header can supply up to 1 amp current to fans. These days, most common case ventilation fans use less than 0.2 amps, so you certainly can connect from 1 to 4 such fans to a single header using a splitter. BUT there is a limit you need to follow, and mobo makers don't want to get involved in that complexity that MIGHT encourage you to overload the header. That is why they don't supply any splitters.

You may find that you cannot find a 3-pin fan splitter, but can find only 4-pin ones. That does not matter - 3-pin AND 4-pin fans can use a 4-pin splitter. Many are around that provide two outputs from one header. There are even ones with 3 outputs, like this:

http://www.newegg.com/Product/Product.aspx?Item=N82E16812423162&cm_re=coboc_fan_splitter-_-12-423-162-_-Product

Two notes to help you.
1. For what you are doing, do NOT get a Fan Hub. Those are different devices, although the simpler ones look a lot like splitters. But a Hub has an extra arm with a connector that you must plug into a PSU power output connector. Hubs like that can ONLY work with true 4-pin systems that use PWM Mode for control. A SPLITTER as I recommend can work with either 3-pin or 4-pin fans and headers, and can handle up to 4 fans on one mobo header without any PSU connector.
2. Any splitter (or Hub) can send back to the mobo the speed signal of only ONE of its fans. The mobo header cannot deal with more than one fan speed signal. If you look closely at the output (male with pins) connectors on a splitter, only one of them has all its pins - the others are missing Pin #3. This is the proper way, so don't worry about it.

 

[kol12]

Thanks guys. Before I get around to using a splitter I should mention that I seem to be having trouble with the two AF140's in their current configuration.

The fan on the SYS_FAN header idles at around 700 rpm but under heavy system load is only doing 800 or so rpm. Similarly the fan on the CPU_OPT header is idling at around 1100 rpm but under heavy load is only doing 1200 rpm. These fans are rated for a max of 1500 rpm, is something not configured right in the bios?

I think I have the same problem with my two Noctua NF-P14S mounted as front of case intake, I've never seen them hit full rpm.

All of these fans being 3 pin should be configured to run as DC correct?

 

[kol12]

I think it's quite possible that Fan Xpert 3 as part of Asus AI suite has control over my fans. I've never bothered with Xpert 3 as the last time I ran the auto tuning feature I wasn't happy with the speeds it set. I set it aside and forgot about it but I realise now that Fan Xpert 3 is active and probably is what has control over my fans. I'll have to play around around with it and see if I can work it out.

 

[Karadjgne]

Asus fan Xpert is by far the best fan control software there is. You can set the fans for whatever temp range you feel comfortable with or want. It will also tell you if you have any control over the cpu_opt header. It's also the easiest to setup, far easier than SpeedFan, works automatically, and has visual setups. Also has fan alarms, which work great for aios, if the fan/pump drops speed, you get notified

 

[kol12]

Asus fan Xpert is by far the best fan control software there is. You can set the fans for whatever temp range you feel comfortable with or want. It will also tell you if you have any control over the cpu_opt header. It's also the easiest to setup, far easier than SpeedFan, works automatically, and has visual setups. Also has fan alarms, which work great for aios, if the fan/pump drops speed, you get notified

Ok I didn't know that Asus fan Xpert was well accepted and I should have realised that it's what actually currently has control over my fans. There is no control for the cpu_opt header.

What is the Auto Tuning? It says to please run the Fan Auto Tuning to get the best customized settings for your fans.

Would changing the CPU fan curves interfere with they way they are set in Corsair Link or would the changes be applied globally?

If I run the two AF140's off of a y splitter it will only be recognized as one fan in Fan Xpert 3 right? Settings that are applied to that header should affect both of the fans? Will the fans pretty much run at the same speed off the splitter?

 

[Paperdoc]

I believe auto-tuning means the fan control software attempts to measure some parameters for the fan attached to the header and then set up that header's control system to optimize the fan performance.

What are you using Corsair Link for? Do you have a liquid cooling system from them to cool your CPU chip? Normally you would install Corsair Link to control that system. If that's the case, using the fan Auto Tuning tool should not really interfere with Corsair Link. However, if you have customized that Corsair software some ways, check after the Auto Tuning to see whether anything did change.

Fan Xpert can only deal with the signals it gets. A splitter will send to the mobo header the speed of ONE of the two (or three) fans connected to the splitter, and the mobo will not know that another fan is also there. The header will send out ONE set of signals to the one fan it knows about on that header, but both fans will get those signals respond in the same way. IF you have connected two identical fans to the splitter, they both will run at virtually the same speed. If the two fans are different, their speeds MAY be different for any set of control signals, but that's OK.

 

[Karadjgne]

Not a fan of Corsair Link at all. I have the option to use it, but prefer the simplicity of the Asus FanXpert to run the entire case. You can run most AIO's directly from the bios, so for most, the Corsair Link isn't even needed.

 

[kol12]

I believe auto-tuning means the fan control software attempts to measure some parameters for the fan attached to the header and then set up that header's control system to optimize the fan performance.

What are you using Corsair Link for? Do you have a liquid cooling system from them to cool your CPU chip? Normally you would install Corsair Link to control that system. If that's the case, using the fan Auto Tuning tool should not really interfere with Corsair Link. However, if you have customized that Corsair software some ways, check after the Auto Tuning to see whether anything did change.

Fan Xpert can only deal with the signals it gets. A splitter will send to the mobo header the speed of ONE of the two (or three) fans connected to the splitter, and the mobo will not know that another fan is also there. The header will send out ONE set of signals to the one fan it knows about on that header, but both fans will get those signals respond in the same way. IF you have connected two identical fans to the splitter, they both will run at virtually the same speed. If the two fans are different, their speeds MAY be different for any set of control signals, but that's OK.

Yeah I have an H80i GT. I believe you have to install Corsair Link to get the usb driver for the H80i to be recognized, probably for the sensors etc. What I am using Corsair Link for is changing the pump speed from quiet to performance mode for gaming as I notice up to a 5° drop in cpu temperature.

The cpu fan profile in Corsair Link is set on Quiet which I think is the default and it seems to work well for me. What I'm unsure of is which software currently has control over the cpu/h80i fans, Fan Xpert 3 or Corsair Link? The profiles for each are quite different

It looks like both AI Suite/Fan Xpert and Corsair Link remain in control of profiles regardless of whether their GUI's are loaded into the taskbar tray.

 

[kol12]

Not a fan of Corsair Link at all. I have the option to use it, but prefer the simplicity of the Asus FanXpert to run the entire case. You can run most AIO's directly from the bios, so for most, the Corsair Link isn't even needed.

An older version that I used was really buggy but when I clean installed Win 10 recently I installed the latest version which seems a bit better. There's a new version that has come out just in the last few days that sounds like it is having quite few problems so I'll hold off on installing that one.

Yes the bios has it's own fan control features right? I've forgotten what it's called, it's an Asus feature I think...

 

[Karadjgne]

No. Every bios has some sort of fan control, only on the most minimalist bios versions is it hidden, but it's still there. Something needs to control the fans.

 

[Paperdoc]

If I understand correctly, the fans that cool your radiator are NOT connected to the Corsair H80i pump system at all. They are plugged into one or two mobo fan headers, right? As far as I know, the Corsair Link software ONLY controls a fan connected to its pump unit. It can NOT do anything with the mobo fan header settings. Only Fan Xpert3 does that.

 

[kol12]

If I understand correctly, the fans that cool your radiator are NOT connected to the Corsair H80i pump system at all. They are plugged into one or two mobo fan headers, right? As far as I know, the Corsair Link software ONLY controls a fan connected to its pump unit. It can NOT do anything with the mobo fan header settings. Only Fan Xpert3 does that.

Yes they are, the water/pump block has fan headers for the radiator fans and then a cable from the water block goes to the CPU_FAN header.

http://www.corsair.com/en/blog/2015/march/h80i_gt_how_to

This is probably why Corsair Link DOES have control of the fans...

 

[kol12]

Veering slightly off topic for a moment, the reason I replaced the two stock AF140L's with the AF140's was because one of the fans bearings were going and the other one made what I thought was a buzzing noise. It seems the buzzing noise has returned and was not the fan after all. The noise is very difficult to pinpoint but I don't think it's any of my fans. I think it's possibly related to my PSU and the noise is being triggered or amplified. Sometimes the buzzing will just cut off and be silent again.

Anyway I can troubleshoot this further?

Edit: I think the noise is definitely coming from my PSU and it's somehow being amplified throughout the case making it sound like it's coming from all directions!

 

[kol12]

No. Every bios has some sort of fan control, only on the most minimalist bios versions is it hidden, but it's still there. Something needs to control the fans.

Yeah my board has Qfan (Asus) but I'm not sure if the Qfan applied settings in the bios interact with Fan Xpert...

 

[Karadjgne]

Bios gets everything started and sets overall parameters. Once Windows starts, and software settings override bios settings. If there's no software control, bios retains it's settings, so fanXpert will override Qfan settings. If you didn't install the fanXpert, you'd still have basic control because of the bios settings.