Can I attach case fan to CPU fan header?

[Bobsy]

Hello all,

This week, I finally put together all the components I purchased back at Black Friday. That's right: my new hardware has been sitting there for the last four months!

Anyhow, I am quite disappointed with the fan control on MSI Z97M Gaming mobo. The board has two CPU fan headers and two system fan headers. It was one of the reasons why I selected this board.

My case is equipped with Noctua fans:
- Front intake: two 3-pin 92mm NF-B9-1600
- Rear exhaust: one PWM 120 mm NF-S12A
- CPU Cooler: one PWM 120 mm NF-F12 (equipping NH-U12S)

Here is the current hook-up:
- Front intake fans are each attached to Super-low-noise adapters (blue ones), then to a splitter, and to SYS1 header.
- Rear exhaust fan is attached to SYS2 header.
- CPU fan is attached to CPU1 header.

CPU fan control is wonderful.

Front intake fan control is fine.

Rear exhaust fan control is a disaster. I cannot reduce voltage lower than 50%! At idle, the CPU fan turns at around 200 RPM while the rear fan goes at about 850 RPM. It makes more noise than my old Antec Tri-Cool, that was set to Low.

Since I have a free CPU fan header, I am considering connecting the rear case fan to this header. I suppose it will be "conservative", meaning that it will spin up when the CPU gets hot. Only problem is if CPU stays cool and GPU (GTX 460 at the moment) generates lot of heat. Any thoughts?

(I should have gone with an Asus board. I won't make that mistake again.)

 

[Essence_of_War]

Can I attach case fan to CPU fan header?

You most certainly can. I'm not familiar with MSI's fan control tools, but if you use windows, the great and mighty SpeedFan might be a useful tool for managing the rear fan independently of the CPU temperature.

 

[Bobsy]

I do use Windows. I will check SpeedFan out. I hope it can read the temp sensors and adjust fan speeds accordingly.

 

[BonzaiDuck]

Yup can use any fan on any fan connector without any ill effects.

No doubt.

Only my opinion, but the OP (or anyone) would be wise to explore the possibilities and limitations of the motherboard's thermal fan control before introducing additional software into the equation, like SpeedFan. I'd consider it a last resort.

I'm guessing that some motherboards may limit thermal fan control to only the first CHA_FAN port (SYS fan -- whatever).

This is where $10 PWM splitters can come in handy, removing the power-draw of fans from the motherboard while using a single fan header (like CPU_FAN) to control all the fans attached to it. The only drawback is the monitoring: for splitters of various manufacture, you're only going to be able to monitor the RPMs of one device, even though the additional devices are controlled through the PWM signal.

 

[Bobsy]

I tried Speedfan, but it's unable to "take control" of the fan speeds. I can only monitor through it. Changing fan speeds has no effect. I searched everywhere in the BIOS for a switch to disable the MSI fan control function but could not find one.

I am going to try plugging the rear fan to CPUFAN2 header and see how that goes.

 

[BonzaiDuck]

I tried Speedfan, but it's unable to "take control" of the fan speeds. I can only monitor through it. Changing fan speeds has no effect. I searched everywhere in the BIOS for a switch to disable the MSI fan control function but could not find one.

I am going to try plugging the rear fan to CPUFAN2 header and see how that goes.

I wish I were more familiar with MSI boards and their fan-control features -- I could advise better.

But at this stage, I wouldn't suggest "turning OFF" the BIOS fan-control features; I suggest you explore them.

Did you install the proprietary software that came with the MSI board? It should have a fan-control feature.

I wouldn't "Diss" MSI boards too readily: MSI made my two GTX 970s and provides AfterBurner for tweaking the cards -- which includes fan-control.

Speedfan requires some amount of tweaking to get it to work for your thermal control and fan-speed features. Having explored that aspect on my own, I suggest you find your way with the MB BIOS and proprietary MSI software. It should be much easier.

And -- take your time, persevere and be patient. You might invest more time than you'd like up-front to make this work. After that -- it's done!

 

[Bobsy]

Thank you for your great advice, BonzaiDuck. I can't deny that I am trying to sort this out rather quickly and that I am not exploring the features very much.

I moved my rear fan to the second CPU fan header and it is wonderful. I have much more control over the fan speed.

The MSI software (Command Center) offers slightly more granular control over fan speed vs. the BIOS, but both control exactly the same things on the motherboard.

The "smart" fan control allows the user to set a specific fan speed % for four different temperatures ranging from 40°C to 80°C. The temp scale does not say which temp (CPU or system?). With the CPU temp showing 45°C and the system temp being 30°c, I decided to test the system fan profile to see which temp it uses. I was quite surprised to see that only the CPU temperature is used to drive all four fan headers. The system temperature does not drive the case fans.

This basically means that, as I was told by several of you here, it makes no difference that I plug my case fan to the #2 CPU fan header. This makes me quite happy.

 

[BonzaiDuck]

Thank you for your great advice, BonzaiDuck. I can't deny that I am trying to sort this out rather quickly and that I am not exploring the features very much.

I moved my rear fan to the second CPU fan header and it is wonderful. I have much more control over the fan speed.

The MSI software (Command Center) offers slightly more granular control over fan speed vs. the BIOS, but both control exactly the same things on the motherboard.

The "smart" fan control allows the user to set a specific fan speed % for four different temperatures ranging from 40°C to 80°C. The temp scale does not say which temp (CPU or system?). With the CPU temp showing 45°C and the system temp being 30°c, I decided to test the system fan profile to see which temp it uses. I was quite surprised to see that only the CPU temperature is used to drive all four fan headers. The system temperature does not drive the case fans.

This basically means that, as I was told by several of you here, it makes no difference that I plug my case fan to the #2 CPU fan header. This makes me quite happy.

Well, think about it. All of my ASUS boards control both CPU and CHA fans (SYS-tem fans, you called them) to reference only the CPU temperature. You can still control fans in two groups: CPU and CHA -- IF . . you have decent fan control of at least one CHA fan port. Personally, I divide them according to Intake and Exhaust, putting the Intake fans on the CHA port(s) and the exhaust (plus CPU) fans on the CPU port.

If you want to worry about individual components, then you're going to install thermistors on hot components and use those temperatures to control this or that fan with an add-on controller. But I've never needed to do that for my best systems.

I may have cited the Aquaero 5 controller, which can be bought just as an internal circuit-board, or for more money has a fancy front-panel LED screen. It connects to an internal USB port, and you'd install the proprietary monitoring and control software. As I understand it, such a controller would also read the sensors on the motherboard. It has its own processor.

But why spend the money? $20 bucks for a couple splitters, carefully chosen PWM fans, and you can do it all from the motherboard.

 

[Bobsy]

I also ended up with my intake fans on the CHA (SYS) ports and the exhaust (plus CPU) fans on the CPU ports.

Would you say that my CPU cooler (Noctua NH-U12S) is installed correctly if:
- the CPU temp is 40°C at idle with CPU and exhaust fans set to 20% speed
- the CPU temp is 30°C at idle with all fans set to 100%
- the CPU temp is about 60°C after 10 minutes of Prime95 with fans running at 50%
?

Thanks.

 

[Essence_of_War]

I also ended up with my intake fans on the CHA (SYS) ports and the exhaust (plus CPU) fans on the CPU ports.

Would you say that my CPU cooler (Noctua NH-U12S) is installed correctly if:
- the CPU temp is 40°C at idle with CPU and exhaust fans set to 20% speed
- the CPU temp is 30°C at idle with all fans set to 100%
- the CPU temp is about 60°C after 10 minutes of Prime95 with fans running at 50%
?

Thanks.

Your temps sound good. Keep in mind that accuracy of the cpu temp sensors gets better as they approach their tjmax, so while you shouldn't rely on the specific number, you certainly sound like you have adequate thermal headroom. Acoustics good at 50% fan?

 

[BonzaiDuck]

Generally, I agree with Essence about the temperatures, with the caveat that I don't know which processor you're using. Went back through the posts, but couldn't find a mention of it.

But whatever it is, 60C under Prime95 load is well below the TCASE thermal spec of between 67 to 74C for a range of processors that include the 4790K Devils Canyon.

 

[BroHamBone]

If you have $30-$40 or so, grab a fan controller. You can probably find to control at least 5 fans....

 

[Bobsy]

CPU is Intel i5-4690K.

The fan speeds of 20% (idle) and 50% (under Prime95 load) are those based on a "smart" fan speed profile set by my motherboard's fan control software. It the CPU temp was to increase past 60°C, the fan speeds would go up to 75%+.

Acoustics at 50% is still reasonable. I care about noise level at idle because I don't want to hear loud fans when browsing the web or sorting photos. The only use case I have for higher CPU usage is gaming (which I rarely have time for, unfortunately), in which case fan noise does not concern me.

 

[bonehead123]

Originally Posted by Bobsy:
Would you say that my CPU cooler (Noctua NH-U12S) is installed correctly if:
- the CPU temp is 40°C at idle with CPU and exhaust fans set to 20% speed
- the CPU temp is 30°C at idle with all fans set to 100%
- the CPU temp is about 60°C after 10 minutes of Prime95 with fans running at 50% ?

Your temps sound good. Keep in mind that accuracy of the cpu temp sensors gets better as they approach their tjmax, so while you shouldn't rely on the specific number, you certainly sound like you have adequate thermal headroom

So I guess my temps of 26c idle & 41c under 10/15mins of Prime 95 are pretty good huh ?

FWIW, I run an i7-4770k @4.2GHZ with 6 case fans 20-50% (3 CM & 3 Swiftek) + an EVO212 cpu cooler & the ASUS AI-3 Suite control settings

And yes, I use splitters to connect them all to the 5x mobo headers.....

 

[BonzaiDuck]

So I guess my temps of 26c idle & 41c under 10/15mins of Prime 95 are pretty good huh ?

FWIW, I run an i7-4770k @4.2GHZ with 6 case fans 20-50% (3 CM & 3 Swiftek) + an EVO212 cpu cooler & the ASUS AI-3 Suite control settings

And yes, I use splitters to connect them all to the 5x mobo headers.....

I have no indication that anything's really changed since Ai-II Suite. ASUS CPU temperature is always about 7 or 8C below those registered by several monitoring utilities like AIDA-64 or HWMonitor.

Otherwise, at that sort of mild overclock -- yeah. But I think it's possible to get the same result with four fans for the right case. paradoxically, the smaller the case, the more effective the airflow with the same number of fans installed in a larger case.

 

[Essence_of_War]

And yes, I use splitters to connect them all to the 5x mobo headers.....

Nice! So your case "breathes"