Fan Control and Idea - is it inherently flawed? Any cautions? (Looking for advice!)

[canadianvice]

So, I think I'm coming toward the end of my adventure regarding fixing the cooling situation in my PC. I've finally discovered the BIOS fan curves, which is doing wonders for the CPU controlled stuff, but I want to try and fix a few small issues + separate GPU control.

So, the PWM for CPU runs into a basic fan controller that's part of my case, and this then splits into 5 or six 3-pin (3P henceforth) headers.

The trouble is, I don't have a reliable way of plugging everything in that isn't awkward. Available to me, I have this fan controller and then SYS_F1 and SYS_F2. I have nothing in those, but I don't think they are reliable for 12V power, since when I opened my checker, they were listing at 0%, despite a 100% curve in BIOS.

I'm using two AIO coolers for purposes of CPU and GPU cooling, but the trouble is that I don't think it's a good idea to use the controller board for the pumps, as they are supposed(?) to run at 100%. I also don't think fan control for the GPU fans being predicated on the CPU is necessarily a great idea either.

So, here's my solution I think I've figured out.
1 Molex -> 4x3P (Part here)

1 PWM-Modulated Molex-Powered Fan controller - Edit: The chinese ones are PWM ONLY, so no conversion I think for 3-Pin control. Does anyone know of a cheap fan controller that has PWM input but can handle speed adjustments for 3 pin fans that may be attached to it?

My thinking is that I can plug the two pumps into the Molex connector to ensure they run consistently. One thing I'm worried about though - Is there a 12V and a 5V molex? How would I tell? Do I cut some wires to make that determination?

Then I'm thinking of connecting the graphics PWM into the fan controller, and using that for the two fans on its radiator. Or is it likely I could just use a splitter and power 2 DC fans (TT Riing 12) straight from the card?

Anyhow, does this seem like a possible solution? Any obvious problems I should be concerned with? Does the fan controller I linked look like it'd be suitable for my purposes?

 

[CountMike]

Molex connectors (like ones for disks) have 12vDC (Yellow) and 5vDC (Red) with Black as common.

 

[Paperdoc]

Let's start with a few naming conventions.

There are ADAPTERS that allow you to convert one type of connection to another, often providing several outputs from a single input. An example is the item you linked with "here" - it converts a single 4-pin Molex female output from the PSU (using only the 12V portion of that) into four male outputs that can supply the fixed 12 VDC and Ground connections to several 3- or 4-pin fans.

There are CONTROL systems built into your mobo and accessed using fan headers. The headers are all male (with pins sticking up from the mobo). All mobo's have at least one such for the CPU_FAN (may have extras) that are guided by the temperature sensor built into the CPU chip itself, feeding its signal to the mobo), plus one or more SYS_FAN or CHA_FAN headers intended for use with case ventilation fans. The simplest of these are guided by a different temperature sensor built into the mobo; more complex ones may have several temp sensors and allow you to choose one sensor for each fan header. Normally each fan header has several configuration details you can customize, but factory default settings usually set the temperature sensor and control targets and configure to use the automatic control systems. These systems for each header concentrate on the TEMPERATURE target for the specified sensor and hardware devices, and constantly manipulate the voltage or PWM signals sent out of the header to change the speed of the cooling fans attached to keep the heat sources at the desired temperature target.

You can buy third-party FAN CONTROLLER modules that you mount on a slot of your case. These connect to the PSU for power and have several output connectors to feed your fans. When using these, you do NOT connect those fans also the the mobo. Most of these give you the ability to control the voltage (or maybe the PWM signal) to each fan. Some also will display for you the speed of each fan. Virtually none of them can access the temperature sensors on the mobo or CPU chip, so there is no way to achieve "automatic" control. SOME more advanced ones do include their own temperature sensors that you can fasten to spots on the mobo that you choose to allow "automatic" control, but then you have to figure out where the sensors should go and what the target temperatures at each should be.

There is another type of manual FAN CONTROLLER system - one that is already built into a case and operates very much like a third-party add-on because it gives you some ability to switch fans and change their speeds manually.

If you have more fans than you have mobo fan headers to plug them into, you can get two types of devices that allow you to connect more than one fan to a header. SPLITTERS simply connect all their fans in parallel to the header. They each have ONE input arm that plugs into a mobo fan header, plus two or more output connectors that you plug fans into. They have no other types of connectors. A mobo fan header usually can supply up to 1.0 A current to ALL of its fans in total, so this limit applies when using a SPLITTER. A HUB has those two types of connectors, PLUS a single third connector that must plug into a power output (either 4-pin Molex or SATA) from the PSU. This latter obtains all the power for the fans from the PSU source which has a MUCH higher limit that a mobo fan header, so it effectively eliminates that 1.0 A limit. However, with a couple of exceptions, a HUB can ONLY be used if its mobo host header actually is using the new PWM Mode of control (and you cannot tell that from the pin count of the header) AND all the fans you connect to the Hub are of the 4-pin design. Neither of these devices is a fan controller - the are only ways to connect many fans to a single controller output.

Fans come mostly in one of two common types. The older type has 3 wires (Black, Red and Yellow) from the fan motor to the female connector, which has 3 holes in it. Its speed can be controlled only by varying the voltage supplied on Pin #2 from +12 VDC (max) down to about +5 VDC - any less and the fan may stall. This is called the Voltage Control Mode or DC Mode of control. The newer design has 4 wires (different color scheme) leading to a very similar connector with 4 holes. In this system the voltage supplied to the fan on Pin #2 is always the full 12 VDC, and the fan also receives via the new Pin #4 the PWM signal. Inside the fan there is a small chip that uses that signal to modify the flow of current from the DC supply though the motor windings to achieve speed control. This is called PWM Mode of control.

Fan connectors and headers have been designed so that you CAN plug any 3- or 4-pin fan into any 3- or 4-pin header, and it will work - within limits. If you always match fan type to header control Mode the mobo header can control its fan's speed. If you mis-match, there are two possibilities. Plug a 3-pin fan into a 4-pin header that actually is using PWM Mode, and the fan gets a full +12 VDC from Pin #2 all the time and cannot receive or use the PWM signal from Pin #4, so it always runs full speed. You get full cooling, but no speed control. Alternatively, plug a 4-pin fan into a 3-pin header and it receives no PWM signal to use to modify current flow. However, the voltage it receives on Pin #2 is varying because the header can only apply the older Voltage Control Mode, and thus the speed of the fan IS controlled by that header.

With that background, back to your post. You start with "So, the PWM for CPU runs into a basic fan controller that's part of my case, and this then splits into 5 or six 3-pin (3P henceforth) headers." I take that to mean that your case came with a Fan Controller unit that has TWO input connections. There must be one cable from it to a PSU output for fan power, and another cable from it to the CPU_FAN Header to pick up the PWM Control signal. Then it has many output male connectors to plug fans into. Now I'm intrigued by your statement that this controller has 3-pin fan headers. By any chance, is this a Phanteks case that came with a Phanteks PWM Hub unit that is mounted somewhere inside your case? That is one of the VERY few Fan Hubs that CAN work with 3-pin fans. If that's what you have, then I know exactly how it works. (By the way, it is not a "controller".)

If you provide us with the maker and exact model number of your mobo we can look up its specs and tell you exactly what its fan headers can do and how to use them.

Similarly, provide us with makers and models of the two "AIO Coolers" used on the CPU and GPU systems. Then we can look up how they should be connected. It IS common for such systems to run the pump unit at full speed all the time and do control of the cooled item solely by changing the speed of the fans on their respective radiators, but not ALL such systems work that way. Additionally, some of those systems depend on using mobo controllers, and others take over control using their own software utilities.

Further, tell us exactly what GPU card you have. I have seen some that operate their own on-board cooling control systems and use standard case fan headers on the video card to connect their cooling fans. In such a system it can be possible to use those video card controller outputs to guide case fans as well as the video card's fans.

I fully agree with your view that controlling case ventilation and / or video card cooling from the CPU_FAN header is not right. There are ways to do it correctly, and we can advise the details once we know all your system components.

 

[canadianvice]

Sorry, cardinal sin. Toms lists most of the fun stuff in my user mouseover, but here's the skinny:

Fans:
- 2 stock corsair 120mm, pwm
- 3 tt riing 12 (120mm); 3 pin control
The tt fans are mounted on the rads. 1xtop-f-in for cpu, and 2xfront-out for the gpu.

Nzxt Manta Case w/ the pre-installed unknown spec fan hub which I have previously called a controller. Basically the hub has:

- power in
- pwm in (for regulating attached fans)
- pwm "special" (the state of the fan attached here is fed back to the mobo for "broken cpu fan" alerts)
- bunch of 3pin fan headers; whatever the non-pwm variety is. I remember this distinctly as things like my pwm case fans needed to be offset.

The hub seems to do dc control on these, as I can tweak my fan curve with software for the cpu and all fans on the hub respond appropriately.

My gpu is a EVGA SC Black 1080ti; I have used a Kraken G12 mounting adapter to attach a Corsair H105 aio for cooling purposes. The original heatsink made use of a half-height pwm (mini?) split to two fans, but I don't think they were huge ones.

My cpu is an i7-6700k, with a h60 aio. Note, in case the idea occurs: unfortunately I can't switch these units, as the h60 does not work w/ the adapter bracket on my gpu.

My motherboard is an MSI Carbon AC Gaming Pro z270I itx mobo.

 

[Paperdoc]

Thanks for those details.

Start with the mobo fan header characteristics. ONLY the CPU_FAN header does PWM Mode control based on the temp sensor inside the CPU chip, and that's all it does - it cannot do DC Mode. Both the SYS_FAN headers do ONLY DC Mode (Voltage Control Mode) control, and these are based on the mobo temp sensor.

Now the CPU cooling. Plug the H60 PUMP unit into the white Port #1 of the fan Hub pre-mounted in your case so that the pump speed is reported to the hub and forwarded to the CPU_FAN header. Your BIOS will report that as the speed of the CPU FAN, even though it really is the pump. The pump WILL run full speed all the time as designed, because that's what a 3-pin "fan" (or pump) does when connected to a 4-pin header that actually uses PWM Mode for control. Now plug the FAN for the H60 system into one of the other Hub ports, and its speed (using 3-pin Voltage Control Mode but based on the PWM control signal from the CPU_FAN header) will be automatically controlled according to the internal CPU chip temp.

You have not talked about any case ventilation fans. Such items could be plugged into the SYS_FAN headers. BOTH 3- and 4-pin fans CAN be controlled by the Voltage Control Mode they use, although 3-pin units are slightly less expensive. But maybe you are thinking that the airflow generated by the two sets of radiator fans provides enough cooling for the case without having dedicated case vent fans.

For the GPU cooling system, I agree that its pump unit should be powered by a fixed 12 VDC supply for full speed constantly. To get that, one option is to plug it into one of the SYS_FAN headers and configure it in BIOS Setup to run at max cooling always. If you do that, the speed shown for that header will be the GPU card PUMP speed.

For the FANS on the Corsair H105 system adapted to the GPU you have a real problem finding the correct control system. Neither the CPU_FAN nor the SYS_FAN headers are based on a temperature sensor in the GPU chip. However, you do have one "freedom" you can use. It appears the fans supplied with the H105 are 4-pin type, BUT that CAN be controlled either by a 3-pin header using Voltage Control Mode, or by a 4-pin header using PWM Mode. So the source header control Mode is not critical. On the mobo, the closest approximation to that may be the sensor on the mobo that controls the two SYS_FAN headers, so you could plug in the two H105 rad fans (using the y-cable supplied with it) to a SYS_FAN header.

But there MAY be a better way. I cannot tell from pictures whether this one is possible. The graphics card you have modified came with two fans pre-attached that you have removed. Look closely at how they were wired to the video card. Did each have a standard fan female connector on the ends of its wires that plugged into a standard male (with pins) connector on the video card? If so, you could simply plug the Y-cable with the H105 rad fans into that video card male fan output to power and control those fans according to the system on the video card itself. (OR, if the card has TWO fan headers, you don't need the Y-cable.) Now, IF the video card's supply to its original fans was not done using a "standard" mobo fan male header (often 3-pin), maybe you can still figure out what signals its contacts do have. What you really need for the rad fans (the Y-cable merely splits this into two parallel feeds for the 2 fans) is a Ground and a + DC V line. In a 3-pin fan system, the Ground connection goes to Pin #1 of the fan connector, and the DC V supply goes to Pin #2. The voltage on that second line in a 3-pin fan system ranges from +12 VDC max down to about +5 VDC (less could stall the fan) to control its speed. This system would provide power and control to the H105 system rad fans, with control based in the GPY chips cooling control system on the graphics card. IF the card has its own management utility that tells you the speed of the fans it came with, this way it would tell you the speed of one of both of the rad fans.