Question Questions about fan Installation and mobo headers ?

[Objektor]

Hello – first time forum member and first time PC assembly. Please bear with me if any of my terms are incorrect, misleading or stupid.

New computer is sitting on a desk, ie; it’s not in a case. I’m running a dual heatsink CPU cooler with 2 x 120mm / 1500 RPM fans attached. Speeds are being ramped up, against temperature changes with custom graphs in the BIOS.

Some extra information: Fan Headers are:

CPU Fan x 1 (Auto Mode) 2A / 24W
Pump Fan x 1 (PWM Mode) 3A / 36W
System Fan x 6 (DC Mode) 1A / 12W

Some matters I’ve been contemplating:

CPU Header vs System Header

After speaking to a couple of unrelated “IT People”, their view is that I MUST have these plugged into the CPU_FAN header. After hours of testing this, along with using the SYS_FAN instead, I can’t seem to produce any difference in fan behaviour. Either way, they both become unstable at around 350-500 RPM, and the motors power down to a stop. I’m thinking that a minimum value of 600RPM will be fine in idle state, with enough headroom to avoid unpredictable shutdowns.

As there are 2 x CPU Fans, but only one CPU_FAN header, a split cable/breakout on one of the fans provides power for the other one. And here’s why I’m considering using individual SYS_FAN headers.. During testing I have been using a custom-built AIDA64 dashboard so I can see RMS values (and CPU Temperature) at a glance. Eventually I’ll set up a small raspberry pi monitor to display the dashboard, but for now it’s on my main screen, and launches at startup. With each CPU fan, I’ll be able to see a failure on one of them. But if I ran them as a split cable install onto the CPU_FAN header, I wouldn’t know if one of them failed, since it’s only reading one of them. This configuration also doesn’t allow for independent control (or monitoring)

It was stated to me that “there will be an error message if you don’t”. and that’s true. A warning is thrown at OS startup if nothing is connected to the CPU_FAN header. But I can turn that off in the BIOS.

Are there any arguments for/against using specific headers ? If anything, I might actually want to plug the two front chassis fans to the CPU_FAN header.

PWM vs DC

After reading plenty about the difference, I can’t determine any real value in PWM mode. The fans behave the same, on either header, and in either mode in the BIOS. And that is that they become unstable <600 RPM and shut down at around 350 RPM. Note that the 6 x SYS_FAN headers are DC only. They seem to do what I expect them to do.

GPU Fan Control

Having never used a discreet graphics card before, I can’t work out what’s controlling the GPU Fans. There’s nothing in the BIOS (I assume because it’s not associated with a motherboard header). I have tried several OS-level apps, but they have since been uninstalled, along with a fresh Windows install. The fans remain still at idle, and kick off around 50-60 degrees (this is a guess, as it happens fast when stress testing.

Does the GPU have it’s own fixed speed control based on temperature, within the GPU’s processor ? I can’t work out any way to find this control data.

Also, what’s the suggested operation for GPU ? I have re-installed AMD “Adrenaline” simply to gain some control (I would prefer as little bloatware as possible). But even through that app, it’s not very customizable, with either a ‘silent mode’ where the fans are off, them rap up beyond 63 degress. This might actually be the default operation, without the software.

In custom mode, I can’t pull the custom curve down to zero, the lowest it will go is 1100 RPM. In other words, they are ALWAYS running.

I’m not very comfortable with either of these options. Is the GPU OK to always sit at zero fan speed until 60 degrees ?

Or, with the other option, are fans ‘always on’ at 1100 RPM going to reduce the lifespan of the motors ?

 

[Aeacus]

With each CPU fan, I’ll be able to see a failure on one of them. But if I ran them as a split cable install onto the CPU_FAN header, I wouldn’t know if one of them failed, since it’s only reading one of them. This configuration also doesn’t allow for independent control (or monitoring)

That's true that you can't tell if 2nd one fails, when you're using Y-splitter. But all you need to do, to verify, is just looking. Also, CPU air coolers with 2 or more fans, do just fine even when 1 fan is operating.

Independent control is actually a bad thing for fans who run in push-pull configuration. Since both fans need to run in sync, in push-pull configuration, to establish the greater static pressure, what one fan otherwise can't do. Now, if you have them spinning at different RPMs, you'd be fighting against the very concept of push-pull.
Due to that, it would be best if you have them running in sync, connected by Y-splitter.

After reading plenty about the difference, I can’t determine any real value in PWM mode.

There are advantages of PWM mode, over DC mode. After all, PWM mode is successor of DC mode.

One such advantage is fine tuning the fan speed.
With DC mode, only way to control fans are by adjusting voltage. Depending on control method, it could be by 1V steps, 0.5V steps or even 0.1V steps (e.g my fan controller: Thermaltake Commander F6 RGB, has voltage control in 0.1V steps). This wouldn't give that accurate control over the fans, since DC fans operate at ~4 to 12V.
PWM in the other hand, can have far minute steps in controlling the fan speed. Since PWM fan in PWM mode gets full +12V all the times, it's the PWM signal itself, that controls the fan speed. There can be thousands of steps within PWM signal.

But for more in-depth explanation, regarding PWM vs DC, i have to summon our expert on fan headers: @Paperdoc , who can give you far better explanation than any of us.

I can’t work out what’s controlling the GPU Fans.

GPU fans are controlled by GPU itself. Usually by following built-in profile, different for each GPU. But there are software out there that can also control GPU fans, like your AMD Adrenaline. MSI Afterburner would be another one. And at current moment, i can't recall if SpeedFan was also able to control GPU fans.

Is the GPU OK to always sit at zero fan speed until 60 degrees ?

Depends on what GPU you have, but for most GPUs, they do fine at 60C. It's 80C and above that you need to worry about.

I have a MSI Gaming X GPU, that has a feature called "Zero Frozr", which means that as long as GPU temps are below 60C, none of the GPU fans spin. This makes GPU noise output to 0dB(A) and also lengthens the fans lifespan. Once GPU temps go over 60C, then the fans start to spin, to cool the GPU. Though, highest i've ever seen out of my GPU is 66C (during benchmark).

Zero Frozr is actually one of the reasons why i bought my MSI Gaming X GPU. I don't need to listen the GPU fans when i'm browsing the web (or typing this reply). Also, like i said, with fans stopped, it extends fans lifespan. My current GPU: MSI GTX 1660 Ti Gaming X 6G is actually my 2nd MSI GPU. 1st one (now retired) was MSI GTX 1060 Gaming X 3G and that GPU too has Zero Frozr feature.

Though, as far as GPU fans go, you can not get a minute control over them as you could get with case fans. Either you use built-in profile, or custom curve. But no absolute control.

 

[Paperdoc]

First, OP needs to tell us exactly what mobo he has - maker and model. With that info we can advise whether there is a way to connect the dual CPU cooler fans individually and still synchronize their actions. That is not necessary, but OP wants it.

Second, Aeacus is entirely correct - the card does its own temperature control by manipulating its fan speed. There never has been any "standard" way to communicate the fan speed on a GPU card to the mobo, or to send it instructions for fan control. MOST makers of graphics cards include in their software utility package a tool to observe and adjust card performance, including how the cooling fan is managed. Such a tool is custom-programmed to access that particular card for this and simply runs as an app under Windows. . Look for that, rather than trying to find a third party software utility.

Regarding DC versus PWM control modes, the major difference is that using PWM Mode actually allows the user to have the fan MINIMUM speed set lower if required (NOT usually needed) because that system basically gives the fan frequent tiny "kicks" of current. The result may be only a small difference in what minimum speed you can get away with without stalling. Besides that factor, a fan designed for PWM operation is best used with that control signal set, rather than DC Mode. Really, having it able to work under DC Mode was only a feature to allow that to be done on older systems that have no PWM Mode, and that was almost entirely for ease of market acceptance when the design was FIRST introduced.

 

[Objektor]

.

Thanks for your very thorough response. I also have an MSI board, but don’t share your enthusiasm for the MSI Centre apps, and feel that the UX is rather awful. Right now I’m using it only for the ‘Mystic Light’ app, for very simple RGB control - one RGB fan that switches color based on temperature, as a subtle visual aid id the CPU starts getting toasty. The individual fan curve control app (User Scenario) is also poorly responsive to end-user interaction

Regarding the cooler fans being co-dependant, and the push/pull operation, I have been giving that some thought during testing as to the best config. In theoretical isolation, you’re likely 100% correct. But that’s not taking into account the significant inflow from the front/top 140mm chassis fan that’s blowing a direct stream of ambient air towards the cooler. At this level of analysis for optimum performance, we would really need to be testing in an engineering lab to determine the ideal RPM.

And anyway, my goal has always been to run those two fans at the ‘same’ speed.

Although the fans are identical in specs, and from the same manufacturer, one of them is an aftermarket purchase (the RGB one). And… they do not run at the same speeds, when attached on their own, out of the same header. It’s only around +/- 15%, and they can be equalized if running from two different headers with different fan curves. I neither expect to tune them as precisely equal, nor widely different in speed. ‘Roundabout the same’ is the goal. And I can’t do that out of a single header.

As for visually observing a failed fan (with two running from a single header), I’m not going to be able to see this when the PC eventually becomes my main computer. It’s going to be standing inside a 19-inch studio rack. There will be a glass side panel, but placement will only really provide visual feedback from the slight RGB glow of my aforementioned temperature-controlled ‘traffic light’ setup. I also mostly use the computer in a dimly-lit environment. Another reason I wouldn’t mind per-header config, to independently monitor each of them.


Thanks for sharing your thoughts and reasoning on GPU behavior. I’m also running an MSI card, and made the deliberate decision to choose components based on (the possibility of) tighter integration. MSI/AMD card, MSI mobo, AMD chip. Turns out that was irrelevant. I think I’m going to run with your preferred setup, and leave the fans off until 50-60 degrees. I’ll also appreciate the quieter decibel levels.

 

[Objektor]

.

I’ve tried all the component-associated software packages from both AMD and MSI. And the MSI Centre ‘User Scenario’ app is absolutely terrible to use. If it wasn’t for the use of basic RGB control, I would un-install everything MSI related. As for the AMD Adrenaline app, I highly suspect the silent-mode option is simply doing the same thing as the card is natively doing (as you described above). So I can probably delete that too.

Apologies for not mentioning the motherboard, as I didn’t think it was relevant. Here’s a link to the manual. The fan header/PWM details can be found on page 36.

https://download.msi.com/archive/mnu_exe/mb/E7C56v2.1.pdf

I’ll have to look again in the BIOS-controlled fan settings, but I believe there was no difference between PWM and DC for what I was trying to do… and that was to bring the RPM down to <500 at idle It might well be that the fan motors just aren’t able to operate that slow. These are CHEAP items.. the RGB version was $10 USD, and it’s non-RGB equivalent would be even cheaper.

 

[Objektor]

As this topic also involves software, folks might appreciate this:

View: https://www.youtube.com/watch?v=uDPKVKBMQU8


I've installed this via github and played around, before un-installing. It's certainly powerful, but a bit unnecessarily complicated. And I dont have the slightest idea how, but it seemed to be responsible for completely bricking some sensors, system-wide. A fresh Windows install fixed that, but I'll need to be very cautious if I explore it again.

This software might end up being my control platform, because it's quite powerful.

 

[SkyNetRising]

I also have an MSI board

Can you list specs of your system?
What cpu cooler are you using? Is it AIO liquid cpu cooler? What model?

I’ll have to look again in the BIOS-controlled fan settings, but I believe there was no difference between PWM and DC for what I was trying to do

If you have 4pin fans and 4pin fan headers, then you use PWM mode.
If you have 3pin fans on 4pin headers, then you use DC mode.

Do not use DC mode on 4pin fans.
And do not use PWM mode on 3pin fans.

 

[Objektor]

Can you list specs of your system?
What cpu cooler are you using? Is it AIO liquid cpu cooler? What model?

Ive stated the cooler details in the first post

"I’m running a dual heatsink CPU cooler with 2 x 120mm / 1500 RPM fans attached".

None of your other questions are relevant to my questions. This is a discussion about fans. Just plain old ordinary fans.

 

[SkyNetRising]

"I’m running a dual heatsink CPU cooler with 2 x 120mm / 1500 RPM fans attached".

I don't know, what you mean by "dual heatsink cooler".
All coolers have heatsinks. Radiator in AIO is a heatsink.

None of your other questions are relevant to my questions. This is a discussion about fans. Just plain old ordinary fans.

CPU cooler model is relevant.
Motherboard model name is relevant, to see what fan headers are available.
Fan type is relevant.
We don't even know, if you have 4pin fans or 3pin fans.

Withholding important system information will limit quality of assistance, you can get.

 

[Aeacus]

but don’t share your enthusiasm for the MSI Centre apps, and feel that the UX is rather awful. Right now I’m using it only for the ‘Mystic Light’ app, for very simple RGB control - one RGB fan that switches color based on temperature, as a subtle visual aid id the CPU starts getting toasty. The individual fan curve control app (User Scenario) is also poorly responsive to end-user interaction

While i do like MSI as a brand (got MSI MoBo and MSI monitor, on top of my MSI GPU), i don't like nor use any MSI software, except MSI Gaming OSD to control my monitor settings.

I did try MSI App Center and while i could control my GPU fans with it a bit + RGB on my GPU, i like the Zero Frozr default feature and i don't care about the RGB on my GPU. The default rainbow on GPU is good enough for me.
I also don't have MSI Command Center (now known as MSI Dragon Center), since while it does have fancy GUI, it flat out won't detect my RAM, and overwrites the BIOS XMP 3000 Mhz, sticking my RAM at 2133 Mhz once Win loads. So, i uninstalled MSI Command Center as soon as i found out that issue and haven't looked back since.

I have been giving that some thought during testing as to the best config. In theoretical isolation, you’re likely 100% correct. But that’s not taking into account the significant inflow from the front/top 140mm chassis fan that’s blowing a direct stream of ambient air towards the cooler.

That depends on the heatsink of CPU cooler. Some heatsinks are closed at the sides, where only one direction airflow is allowed to pass it. This way, fans blowing/sucking from the side doesn't matter. Other heatsinks are open from the sides and side airflow can matter in some degree.

My CPU cooler: Arctic Freezer i32 (amazon link with pics) is closed on the sides, so, for me, my 3x 140mm top exhausts won't interfere that much with my CPU cooler. Also, i have plenty of space between top exhaust fans and CPU cooler (since i have full-tower ATX PC case, Corsair 760T V2 Black) and i've replaced the stock fan on CPU cooler with 2x 120mm Corsair ML120 Pro LED fans, which have far higher airflow and static pressure than the stock fan ever had.
I'm using default profile on BIOS (if i remember correctly) and have both fans on their separate header, since i have CPU_FAN and CPU_FAN2 headers (two of them). Thus far, my i5-6600K has been running smooth, often at ambient temps (~26C). Most what i've seen out of my CPU was ~ high 60C.

Although the fans are identical in specs, and from the same manufacturer, one of them is an aftermarket purchase (the RGB one). And… they do not run at the same speeds, when attached on their own, out of the same header. It’s only around +/- 15%, and they can be equalized if running from two different headers with different fan curves. I neither expect to tune them as precisely equal, nor widely different in speed. ‘Roundabout the same’ is the goal. And I can’t do that out of a single header.

If you have plenty of free fan headers, sure, you could hook the 2nd CPU fan to SYS_FAN header. 4-pin PWM fan will work just fine in DC mode as well, despite what SkyNetRising above says. Heck, all my fans are 4-pin PWM fans, while 6x of them are controlled by DC (hooked to my Thermaltake Commander F6 RGB fan controller).

I don't know, what you mean by "dual heatsink cooler".

Any twin tower air cooler. E.g NH-D15, Dark Rock Pro 3/4, Assassin III etc.

Motherboard model name is relevant, to see what fan headers are available.

OP has MSI B550-A PRO. (Fished it out from MoBo manual.)

 

[SkyNetRising]

OP has MSI B550-A PRO. (Fished it out from MoBo manual.)

I find this quite annoying and counterproductive, when person asking for assistance refuses to provide relevant system info and
you have go through all the posts, find some linked document and then extract board model name from it.
All of that info should have been provided in initial post.

Ok, we have managed to fish out board model name at least.
This means all fan headers are 4pin.
But still no info on fan type being used.

 

[Aeacus]

I find this quite annoying and counterproductive, when person asking for assistance refuses to provide relevant system info and
you have go through all the posts, find some linked document and then extract board model name from it.
All of that info should have been provided in initial post.

I'm indifferent about it. When sys info is needed, i ask it in my 1st reply. If question is general in sense, which can be answered without knowing the exact components, then i don't mind not knowing exact components.

And I dont have the slightest idea how, but it seemed to be responsible for completely bricking some sensors, system-wide. A fresh Windows install fixed that, but I'll need to be very cautious if I explore it again.

As said by solo dev behind that FanControl software (shown by JayzTwoCents);

Please note that this is a small personal project. It works great for my needs but I didn't test it on a hundred different motherboards. Take it as it is. If it works on your current setup, well you got your fan control situation sorted at least until you change your motherboard!

Source: https://linustechtips.com/topic/1099996-fancontrol-my-take-on-a-speedfan-replacement/

With list of currently confirmed working MoBos there as well. Your B550 isn't part of it (at least, not yet confirmed/denied).

 

[Paperdoc]

OP's reluctance to provide details is a hindrance, but we can work with what has been provided now. The statement that the fans operate identically whether the MODE is set to DC or PWM tells us they must be 4-pin PWM-style fans. So the headers really SHOULD be set to PWM Mode. And that DOES matter, since one significant advantage of that mode is that it allows a lower minimum speed which is one of OP's desires. Still, OP needs to exercise caution in making that setting. Putting it right on the edge of stalling risks causing it to stall from time to time. NORMALLY if that happens the automatic response of the header circuit is to send out a "full speed" signal to ensure the fan re-starts, then to reduce that signal to what it was before. But that means it has re-established the exact setting that caused the stall, so it may stall again. And repeat. There's NO reason to "live on the edge" like that.

OP uses the label "dual heatsink CPU cooler", which I take to mean a CPU cooler with a heatsink and dual fans, one on each side of the single heatsink.

Now to the issue of separate connections for the two CPU cooler fans. This CAN be done with this mobo. See the manual p. 57 - 58. It shows that, for ANY fan header there is an option to select exactly which temperature sensor it is using for guidance. (This probably does NOT apply to the CPU_FAN header - normally that is ONLY allowed to use the CPU temp sensor.) But, OP, you
CAN connect one of your CPU cooler fans to any unused SYS_FAN header. Then go to that header's configuration screen and set this option to use the CPU sensor, NOT the mobo sensor. Now configure this header to the SAME settings as the CPU_FAN header, then make any custom adjustments you need for your speed-matching plan as you outlined. This gives you individualized speed control for those two fans and ability to "see" the speeds of both. NOTE this, though. If these fans really are different, the fact that you can get them to operate at the SAME speed does NOT guarantee that they will both cause the same air flow rate. However, that's pretty insignificant here. You recognize that ‘Roundabout the same’ is good enough. Besides, in this arrangement the flow through the two fans on either side of the heatsink MUST be the same: what goes in must come out!

 

[Aeacus]

OP uses the label "dual heatsink CPU cooler", which I take to mean a CPU cooler with a heatsink and dual fans, one on each side of the single heatsink.

I still get a feeling that CPU cooler is twin tower. And there being 2x 120mm fans, is most likely Scythe Fuma 3, Cooler Master MasterAir MA620P or similar. NH-D15, Dark Rock Pro 3/4 and Assassin III have bigger than 120mm fans on them.

NORMALLY if that happens the automatic response of the header circuit is to send out a "full speed" signal to ensure the fan re-starts, then to reduce that signal to what it was before. But that means it has re-established the exact setting that caused the stall, so it may stall again. And repeat. There's NO reason to "live on the edge" like that.

+1.

My fan controller sends out loud beeping noise when it detects fan not spinning. Also, every power-on, my fan controller feeds full power to all connected fans, to test if they work. Latter is not only for my Tt Commander F6 RGB fan controller, but also feature of NZXT Sentry 3 fan controller (in my Haswell build) and even Aerocool X-Vision fan controller (in my old AMD build).

To get low RPMs, better to buy those fans that are actually capable spinning ~100 RPM, rather than trying to achieve it with fans that start from ~600 RPM or so.

 

[Objektor]

While i do like MSI as a brand (got MSI MoBo and MSI monitor, on top of my MSI GPU), i don't like nor use any MSI software, except MSI Gaming OSD to control my monitor settings.

My mistake. When you mentioned Zero Frozr, my presumption was through using MSI's software (as it is a feature in the app). But if the card has the feature built in, that's one less reason for me to use MSI's awful utility.

I did try MSI App Center and while i could control my GPU fans with it a bit + RGB on my GPU, i like the Zero Frozr default feature and i don't care about the RGB on my GPU. The default rainbow on GPU is good enough for me.

My GPU doesnt have any RGB, nor do any of the core components. For the most part I find RGB to be a bit cheesy, and the addition of a single cheap aftermarket ARGB fan is for use in a practical & meaningful way, as a visual feedback for temperature changes.

If you have plenty of free fan headers, sure, you could hook the 2nd CPU fan to SYS_FAN header. 4-pin PWM fan will work just fine in DC mode as well,

Which brings me back to the key subject in this discussion. Why do I need to use the CPU_FAN header at all ? I have 6 x SYS-FAN headers, and there will be six fans in the build. To my mind, it seems more logical to manage them in banks/pairs of two, for easy recollection

SYS_FAN 1/2 - Cooler fans
SYS FAN 3/4 - Front Fans
SYS FAN 5/6 - Rear Fans

 

[Paperdoc]

Regarding low fan speeds, you are right. Knowing what you want BEFORE buying and then finding that is best. I'm guessing OP did not consider such things.

Related comment: why does anyone care for the lowest possible speed? Running that way gives you the MINIMUM possible cooling, which really should be used only at system idle. It gives you minimum noise, but most fans are VERY quiet at modest low speeds, and become noticeably noisy at high speeds. If you value low NOISE, include that in your initial parameters for choosing a fan! If your concern is low power consumption, what FANS consume it minuscule compared to the rest of your system! SIX common fans consuming max 0.16 A current each will use 12 W at constant full speed. You might use that much cooling in a big system at max workload that consumes over 500W under those usage conditions.

About system response to fan stalling, I was posting about what most MOBO systems do. I did not consider what third-party controllers do. Some will do what mobos do, but some will do other things. I also skipped a small detail on mobos. Upon fan failure (that is, no speed, or speed below some threshold) the FIRST response is to attempt a re-start as I wrote. IF that works and produces a reasonable speed reading, end of story for now. But IF the result still is NO speed, then the system will place a prominent warning message on the screen (MAY put out a "beep" signal IF your mobo has a small speaker) so you know there is a problem. On most mobos if the failure is the fan on the CPU_FAN header specifically (and maybe the CPU_OPT and AIO_PUMP headers) there will be further more drastic actions to prevent rapid CPU overheating leading to permanent damage. So for most mobo systems, screen warnings etc. draw attention to a failed fan that already has failed the simple "solution" of trying to re-start it. Exactly how any particular third-party fan controller handles these details should be included in the info for that unit, although I recognize that many manuals are short on details!

 

[Paperdoc]

Objektor said, "Which brings me back to the key subject in this discussion. Why do I need to use the CPU_FAN header at all ? I have 6 x SYS-FAN headers, and there will be six fans in the build. To my mind, it seems more logical to manage them in banks/pairs of two, for easy recollection".

Because the SECOND and very important function of any fan header is to detect and deal with fan FAILURE. ALL fans generate and sent back to the mobo header via Pin #3 their speed signal - a series of pulses to be counted. My posts above deal with the common response by such a header to fan failure - that is low or no speed signal. I alluded to "more drastic actions" by the CPU_FAN header, so here is more detail. IF such failure is detected by that header the warning message system is the first response. But shortly after that on MANY (not all) mobos the system will shut down completely without even waiting for the temp sensor inside the CPU chip to report high temperature. That temperture can rise VERY rapidly with NO cooling, so this shut-down is to prevent permanent CPU damage from overheating. Moreover, many such systems also will not allow you to boot up if the CPU_FAN header receives NO fan speed signal immediately on start-up.

As an aside, there is another CPU protection system that comes into play if there IS fan function working, but the CPU chip iternal temperature still goes above certain limits. First stage in this case is to throttle the entire system speed substantially to reduce workload and heat generation. If temperature continues to rise above a second limit, then it will shut everything down. This process is MUCH slower than the process for complete fan failure. It is sufficient for slow temperture rises due to poor cooling, but not quick enough to deal with NO cooling.

These "more drastic actions" are NOT done by any other mobo fan headers. Even if you use the otions some mobos (such as yours) have to specify that a SYS_FAN header should use the temp sensor inside the CPU chip for guidance, that header still will NOT take those extra cautious actions to protect your expensive CPU chip if its fan fails. THAT is why your CPU cooler should always be connected to the CPU_FAN header.

 

[Objektor]

OP's reluctance to provide details is a hindrance, but we can work with what has been provided now.

There's no reluctance or evasiveness on my part. In m first post I've detailed the size, RPM of the fans. Also in the first post I've detailed every single mobo header, including the wattage, amperage and operation mode. You asked for the motherboard model, and I provided a direct link to the manual, with a page number to save you some time, for the section you might have found relevant. I don't know what else to tell you about the fans, they are very cheap, likely generic components, rebranded with the cooler company's logo. What detail have I omitted here ? Whether they are PWM/DC ? Every fan I've looked at is PWM, I'm asking about PWM, and as you've mentioned previously, DC is 'old tech', so on a new build, with new parts, not sure how likely it is that I would even have DC-only fans.

The cooler is a Peerless Assassin - but I still don't see the relevance in this information. I'm not asking 'whats the best temp/fan/RPM' for this model, as it's something I'll be working out for myself, based on my own CPU's temperature performance, the design of the case, the loads I apply to the computer and a whole other range of unique variables.

Both you and Aeacus have been very helpful, and I appreciate the exchange of knowledge. But we're getting nowhere by constantly chastising me for supposedly hiding information. I've blocked that other person from view, as all they seem to want to do is be arguementative. I don't have the mental bandwith for incendiary garbage.

Putting it right on the edge of stalling risks causing it to stall from time to time.

/snip

There's NO reason to "live on the edge" like that.

100% agree. Maybe I wasn't very clear in an earlier post, but that's precisely what I was referring to here:

"enough headroom to avoid unpredictable shutdowns"

I've already found that low-end point of stability, prior to creating this post. While the goal was 500 RPM, this is one point/factor up from where they become very unstable, and two factors above stalling. For these considerations, 600 RPM is a reliable speed. They are a little bit noisy at this rate than I would have liked, but I can live with it.

Down the road, maybe in 2024, if I want a quieter system I'll investigate better quality fans, but until the computer becomes by 'daily driver', and I'm able to log data in real-world use scenarios, then the budget fans I have right now will do the job.

Now to the issue of separate connections for the two CPU cooler fans. This CAN be done with this mobo. See the manual p. 57 - 58. It shows that, for ANY fan header there is an option to select exactly which temperature sensor it is using for guidance.

Correct.

you CAN connect one of your CPU cooler fans to any unused SYS_FAN header.

Thanks, this circles back to the OP. But why do I need to use the CPU Fan header at all ? This is what I'm not understanding. Plugged into SYS_FAN 1/2 , they appear to be functioning precisely the same.

 

[Objektor]

Regarding low fan speeds, you are right. Knowing what you want BEFORE buying and then finding that is best. I'm guessing OP did not consider such things.

Ive spent close to 80 hours researching, learning about computer electronics, tabling comparative component specs across 10 spreadsheets, checking QVLs, sourcing reviews and shortlisting products to purchase, made mock up graphics to check component clearances, calculated power consumption estimates and more.

This has not been a half-assed or inattentive project.

Alas, you are right. I didn't give much thought to fans at all, because there's been no major spend on fans. The case comes with two cans, and the cooler comes with two fans. Since I wanted a rear exhaust, I simply bought what I believed to be an identical fan to the cooler's unit, but with RGB. A measly $10, knowing full well that I might revisit a more complex and higher quality fan system later. That will likely be the Corsair iCUE system, because I would like to incprporate independent tempeartre sensors (one for external/ambient temps, an another for a component unrelated to the computer).

WIth the parts I currently have, there's absolutely no concern on my end about keeping temps. in check. If they need to run a bit faster, so be it. I have NO PROBLEM with the budget fans at the moment, and simply want to know why I've been told that I MUST use the CPU header.

 

[Paperdoc]

We've been typing at the same time. So the answer to your last query was in my post just above it. I comes down to a choice of two options.

1. Use a Splitter to connect BOTH CPU cooler fans to the single CPU_FAN header. This will guarantee that those two fans get exactly the same signals and should perform nearly identically. However, you say they do not do that exactly. Moreover, when you use a Spltter or Hub, only ONE of those fans can report its speed to the host header where fan failure is monitored, so possible failure of the SECOND fan cannot be detected.

2. Use a SYS_FAN header for the second CPU fan only, with the first one plugged into the CPU_FAN header. Configure the SYS_FAN header for this second CPU cooler fan just like the first fan on the CPU_FAN header, except that you want a custom curve to make it run exactly like the first. This lets you make a correction for the fact the fans are not really identical. It also means that second fan WILL be monitored for failure, too, because it can send its speed to that SYS_FAN header. The only item you lose is the extra-cautious drastic actions if that second fan fails -you WILL get a warning message, but not a quick system shut-down. Since the FIRST fan still will be running, you would not have lost ALL cooling of your CPU, so failure of only the second fan does not really require rapid shut-down.

 

[Objektor]

We've been typing at the same time.

haha yes, our responses to each other are all over the place, timing-wise. It;s going to be a strange one for others to folllow

If the only purpose of the CPU Fan header is to throw an error alert, then that's a good reason to consider.

I'm keen on finding out more on what @Aeacus mentioned earlier about a buzzer sounding on fan failure. This sounds like a great idea for ALL of the fans, but I guess it will require a third party hub and control system.

Anyway, since the last post, everything is now in the case, the panels are attached, and it's ready to start testing and setting up properly. I fully expect higher idle temps now that it's not sitting on the bench, so I'll get on to setting up the fan curves when I return from work this evening.

Thanks again for your patience, there's some helpful information that I'll refer to in the future. And apologies again for not being more detailed in my first post.

 

[Paperdoc]

Well, that rapid shut-down feature on fan failure is not the only purpose. On virtually all mobos the CPU_FAN header is set to use ONLY the temp sensor inside the CPU chip, so it IS the one to use first for controlling CPU cooling. Your case is special - a desire to use a second separate fan header for CPU cooling in addition to the first fan. The ability to have a SYS_FAN header change to use the CPU's temp sensor makes that easy for you. That was why I said at the outset we need to know your exact mobo - I was hoping it has that feature.

The buzzer alarm is interesting and useful. I do not recall seeing a MOBO that does that, but could be. However, in that latter scenario it would work only if the mobo has its own buzzer to use. So many mobos now omit that unit, but allow you to add one you buy separately and plug into the SPKR pins of the Front Panel Header. They are cheap and I have one, but I had to add it. It is useful for hearing "beep codes" from the POST process that indicate success or problems in start-up.

 

[Aeacus]

But why do I need to use the CPU Fan header at all ? This is what I'm not understanding.

There is no requirement to use CPU_FAN header at all. There are systems out there that doesn't have anything connected to CPU_FAN header. Mostly AIO CPU cooler systems, when MoBo has separate header for AIO_PUMP. In these systems, user has to disable CPU_FAN header warning from BIOS.

But one reason why to use CPU_FAN header would be the automatic actions MoBo takes, when there's fan failure (Paperdoc explained it more in-depth).

I'm keen on finding out more on what @Aeacus mentioned earlier about a buzzer sounding on fan failure. This sounds like a great idea for ALL of the fans, but I guess it will require a third party hub and control system.

As i've already mentioned, i'm using dedicated external fan controllers, to control most of my case fans. Though, you'd need external 5.25" bay for that.

Tt Commander F6 RGB specs: https://www.thermaltake.com/commander-f6-rgb.html

It has 6x channels, 6x temp probes (one for each channel) and besides beeping loudly when fan fails, you can also set temp target for each of the temp probe. So when the temp threshold is surpassed, it will beep loudly as well, while the channel which detected the high temps, will flash on the screen of the fan controller. It has other features as well, like being able to plug LED strip to channel #6 (in place of the fan) and control the LED of the LED strip from fan controller itself. Since i have NZXT HUE+ with LED strips, i don't use the LED strip feature of my fan controller.

Spoiler: Pic too, because why not (click here to view)

Left: Skylake build with Thermaltake Commander F6 RGB fan controller (that red LCD screen with 6x knobs)
Middle: Haswell build with NZXT Sentry 3 fan controller (LCD screen is touchscreen)
Right: AMD build with Aerocool X-Vision fan controller (LCD is not touchscreen, instead that big knob is used to navigate channels)

Close-up of my Tt fan controller, so you can see what it shows;

As of why i like to use fan controller, compared to fan hub or software control. Well, fan hub just mirrors signal of one fan, making all fans run in sync. With fan hub, individual fan control is impossible. And i also don't like software control either. Since software control comes down between BIOS or 3rd party software. Monitoring fans from BIOS is inconvenient. And 3rd party software has issues. Either not working properly or overly complex to set up/use. Due to that, i prefer manual and individual control, hence why i'm using a fan controller.

 

[Objektor]

i'm using dedicated external fan controllers

Whoa, that's some amazing setups you're running there ! On first glance, I thought they were car stereos.

Advanced fan gadgets aren't something I've looked at too often, since I don't think I'll ever need more than six fans, and that will all be handled by the motherboard headers. I'm not into gaming, so there will be no sustained heavy load applied over long periods (only heavy loads for short durations of up to minutes at a time). Have only briefly looked at products like the Corsair iCUE ecosystem, and presumed that 'controller' and 'hub' were interchangeable terms. This is the first time actually seeing actual controllers, with tactile adjustment pots. Very cool, but probably not something for me.

I may as well show off my PC, since I just sorted out the cables and assembled the case

And yes, the eagle-eyed viewers might notice I'm plugging into the system headers after all. This isn't necessarily a permanent configuration, as I will revisit the project to cut the fan cables to shorter lengths. Haven't been able to find a supplier for plugs/pins, and I don't even know what these plugs are called. That's a task for another day. I'll also install a rear 120 exhaust fan soon, and maybe a top/rear 140

 

[Objektor]

@Paperdoc @Aeacus

And here's some screenshots from the AIDA64 dashboard I'm building. Captured with the case fully assembled. The graph is a visual representation of RPM for the 2 x CPU cooler fans. The have been speed-tuned to near-enough equal.

First screenshot is in idle state for five minutes. Don't know what caused the small spike, probably a background app trying to 'phone home'. Not sure I care enough to investigate.

The second screenshot represents those two fans with a CPU stress test load at 1 minute intervals. Running this stress-test (also AIDA64), the CPU never exceeds 65 degrees.

Eventually I'll buy this utility and add the graphics card to this dashboard, but it's currently disabled in the trial version.