Case fans not showing any RPM readings

Toggle sidebar Toggle sidebar
Status
Not open for further replies.
L

Lawrence Lim

Reputable
Jan 24, 2015
13
0
4,510
Hi there, this is my first build, I'm not really sure whether what's happening is correct or I did something wrong..

I have an NZXT Noctis 450, with the 4 case fans connected by a PWM hub.
My mobo is MSI H170 Gaming M3 which has CPU Fan 1 and CPU Fan 2 headers.

Connected stock intel cpu cooler via CPU Fan 1 and the 4-pin PWM hub via CPU Fan 2. (And PSU is connected to the PWM hub as well)

I was wondering why the case fans on CPU Fan 2 do not register any RPM reading (via BIOS or via SpeedFan, both show 0rpm) .. Am I doing something wrong? Thank you!

Just checked HWMonitor there are 3 things:

CPUFANIN = ~1047 RPM
FANIN0 = 0 rpm
FANPWMIN0 = 38% constantly

***update: I connected cpu fan to pwm hub extn, and then connected pwm hub to cpufan1 with psu molex connected, all seems well now. thank you!

what does this mean?? Thank you!!
 
Solution
P
Normally, you should connect the CPU cooler only to the CPU_FAN port which will (if you don't change the default setting) automatically control that fan and reports its speed. A CPU_OPT port usually is used for a second CPU cooling fan and may NOT display a fan speed.

Normally you would connect all your case ventilation fans to SYS_FAN ports and they would show you fan speeds. You are using a fan hub, so if you connect that to one SYS_FAN port, it should be able to show you one fan speed. With any hub, only ONE of its fans gets to have its speed displayed - the fan plugged into Hub Port #1. All the fans on a hub usually run at similar speeds.

I suspect you may be using, specifically, the Phanteks PWM Hub, but maybe not. I know that...
Sort by date Sort by votes
P

Paperdoc

Polypheme
Ambassador
Oct 19, 2006
11,293
1,042
69,340
Normally, you should connect the CPU cooler only to the CPU_FAN port which will (if you don't change the default setting) automatically control that fan and reports its speed. A CPU_OPT port usually is used for a second CPU cooling fan and may NOT display a fan speed.

Normally you would connect all your case ventilation fans to SYS_FAN ports and they would show you fan speeds. You are using a fan hub, so if you connect that to one SYS_FAN port, it should be able to show you one fan speed. With any hub, only ONE of its fans gets to have its speed displayed - the fan plugged into Hub Port #1. All the fans on a hub usually run at similar speeds.

I suspect you may be using, specifically, the Phanteks PWM Hub, but maybe not. I know that the instructions for that device specifically recommend that you plug its 4-pin female fan connector into the CPU_FAN port, and then plug the CPU cooling fan into Hub Port #1 so its speed can be reported to the mobo. They advise this because SOME mobo SYS_FAN 4-pin ports actually are not true 4-pin, and fail to provide the PWM signal the Hub MUST have. I recommend you do it differently and observe carefully whether it is working correctly.

Plug only your CPU cooling system into the CPU_FAN port. Plug the 4-pin female fan connector from the Hub into one mobo SYS_FAN port, then connect all your case ventilation fans to that, making sure to plug one of them into Hub Port #1. Watch carefully as you turn on the system. The case fans all should start up at full speed for a second or so, then slow down. Later, as the system warms up, those case fans all should speed up. If this is what happens, you are all OK. If, instead, all the case fans start and run at full speed all the time, then the Hub is not receiving a PWM signal from the SYS_FAN port. In that case, you will have to follow the original instructions to get all fans under automatic mobo control.
 
Upvote 0 Downvote
Solution
L

Lawrence Lim

Reputable
Jan 24, 2015
13
0
4,510


thank you so much for your extremely detailed instructions and explanations!

After I referred back to the casing manual, it did state for me to connect CPU cooler to a white header on the PWM which I will assume is the Hub Port #1 you are talking about.. They also provided another option which is for me to use the SYS_FAN by putting any fan on the Port #1 which was meant for the CPU Cooler. (I have not done this)

At the present, the CPU Cooler is connected as per the manual, on white header (Port #1) and the PWM cable connected to CPU Fan 1 header on the mobo, with ext power connected via the molex. I believe this would mean that the casing fans are in sync with the cpu cooler?

For now the HWMonitor software does show my casing fan running at ~1500RPM which can vary ... I would think this is fine? Maybe I will leave it as it is for now instead of shifting to the SYS_FAN port as that does not have PWM from what I noticed in my mobo manual..
 
Upvote 0 Downvote
P

Paperdoc

Polypheme
Ambassador
Oct 19, 2006
11,293
1,042
69,340
You are right. With all your case ventilation fans connected to that Hub along with the PSU fan, they all are under control of the CPU cooling system fan controls. They are based on a temperature sensor built into the CPU chip itself. That is not exactly ideal, but pretty good. The heat generated by the entire mobo system (and hence needing case ventilation) is closely related to the cooling requirements of the CPU chip, so it works. Since there is nothing connected to a SYS_FAN port, I expect what you see in the HWMonitor is the speed of the CPU fan IF it is connected to the white Port #1.

You really should have the CPU cooling fan on the white Hub port. Why? Well, in addition to controlling the speed of the CPU cooler via the CPU_FAN port, the mobo does two extra things specially for the CPU cooler since the CPU is so vital. It monitors that fan's speed to be SURE it has not failed, and will put out an alarm if it does not get a speed signal. (That, in itself, is a reason to be sure the white port has a fan on it.) Many mobos go further: if the CPU cooler speed signal fails, it does not wait for the CPU temperature sensor to show overheating. It puts out the alarm and in a very few seconds simply shuts down everything, and will refuse to start up again until it gets a good speed signal there. These are important and valuable protections, so you need to ensure that the speed signal the mobo checks for this IS the actual CPU cooling fan.

If you want to leave it this way and not worry about other ways, that is fine. Your system will perform well and get proper cooling. Thanks for Best Solution.
 
Upvote 1 Downvote
L

Lawrence Lim

Reputable
Jan 24, 2015
13
0
4,510


Wow, I really have learnt a lot from what you have just mentioned. Really appreciate the time you have spent in crafting such a detailed reply to my query, and rest assured I have benefited a lot from it!! :)

Understanding the processes the mobo goes through makes it easier to know which connections are the ideal ones..

I do have utilities in the taskbar (CoreTemp) to monitor my CPU temperature for fear of the fan situation going awry, but so far it seems to function as intended. I have earlier relocated my CPU cooler to the white header (connected with an extension cable thoughtfully included by NZXT...) and it seems to function fine. I can see all fans spinning through the casing window, further assuring me.

Anyways, I can't thank you enough for shedding light on this for me. Thanks so much!!
 
Upvote 0 Downvote
L

Lawrence Lim

Reputable
Jan 24, 2015
13
0
4,510


May I ask one more question?

Via HWMonitor I can get RPM readings for CPUFANIN (I would think its the stock CPU cooler), can I assume that this RPM speed is applied to all my fans connected to the PWM hub? (ie CPU fan and 4 case fans) ie: my 4 case fans are in sync with my stock CPU fan?

Is it right to think that due to CPU fan being on PWM hub with my case fans, I am not able to control the case fan speeds independently?

Thank you very much!
 
Upvote 0 Downvote
P

Paperdoc

Polypheme
Ambassador
Oct 19, 2006
11,293
1,042
69,340
You are right that they cannot be controlled independently. The single PWM signal the Hub gets controls all of it fans. If you have the Phanteks PWM Hub as I suspect, what it really does is use the PWM signal internally to create six 3-pin fan ports operating in Voltage Control Mode. Thus it can control 3-pin fans. But also, because the new 4-pin fans have a backwards compatibility feature, they also can be controlled by this Hub.

However, it is not true that each fan will run at the same speed. Each fan is supplied with exactly the same voltage by the Hub. What speed it runs, given a particular voltage, depends on fan design, the condition of its bearings, and a few other factors. But none of that really matters. What is important is not fan speed, it is temperature of important components in your system. Connected up as it is, the system will force the CPU fan to provide whatever cooling is necessary to keep the internal temperature measured in the CPU chip on target. All your case fans will run at similar speeds and this is very likely to keep the rest of your system at reasonable temperatures, also. The actual fan speeds to achieve this do not matter.
 
Upvote 0 Downvote
Status
Not open for further replies.

TRENDING THREADS

Latest posts

Moderators online

Share this page

COMPANY
RESOURCES
FOLLOW
Top Bottom