Are case fan hubs safe to use?

[jwburks1976]

I've never used one before, and I don't like the idea of some 15-20$ device killing 1000$ worth of components.

The highest rated (on Newegg) is this:
https://www.newegg.com/Product/Product.aspx?Item=N82E16811999309

Looking up a review, I found this video:
https://youtu.be/RVIM58Tsg7k

Granted, I don't know this guy/gal, or what's up with that smoke, and all the tape on the wires...

 

[why_wolf]

I use the first one. Silverstone is reputable brand.

 

[jwburks1976]

Nothing has burst into flames on you yet? :-D
I just wanted to be sure. Maybe this guy in the video didn't know what he was doing... not that I do, either.

 

[why_wolf]

Yeah no problems. Frankly when it comes to spectacular failures unless you see multiple people reporting the same problem its far more likely to be a freak accident than a QA problem.

 

[Paperdoc]

Yes, Hubs are safe, and Silverstone is a reputable maker. The key characteristic of a HUB like that is that it gets all of the power for its fans directly from the PSU, and thus avoids the limit on amperage available at a mobo fan header. It still gets the control signals from the mobo, though. A Hub system like that can ONLY be used to control the speed of fans IF you're using them in a 4-pin fan system. That means: (a) all the fans must be of the 4-pin design; and, (b) the mobo fan header it plugs into must be configured to use the newer PWM Mode for control, and not the older Voltage Control Mode or DC Mode.

 

[jwburks1976]

What would happen if I hooked a 200m fan to a hub... and then added, say, 4 140mm fans?
Would they work correctly, or would the whole thing burn up in flames?
I've been looking for an answer to this for days, and I am having no luck. I found exactly one discussion on the subject, but it led to nowhere, with no definite answers.

Here's what I'm planning to do...
Get a Thermaltake Core v21 case, because I can lay the motherboard horizontal and put an NH-D15 on it.

A Noctua 200m fan in the front, a 140m Noctua fan in the back, 2x 140m Noctua fans on the right side blowing in (or... 2x 120m Noctua fans on the top right blowing down, I don't know which would be better)...
The front 200m fan + the back 140m fan + the 2 on the top/right, hooked to a fan hub and plugged into sys_fan1, and set to cool the CPU & Motherboard...
Then 2 140m fans on the left blowing into and onto the GPU, setting that to ramp up when the GPU gets hot.

Only have 2 chassis fan connectors. I hate mATX boards for that reason, but I'm also tired of giant heavy cases. I need something more compact, and I'm trying to make the most of it.

 

[Paperdoc]

Yes, a HUB will work because it gets power for all its fans via a connection directly to a PSU power output, and that source can supply much more current that a mobo fan header can. The Hub actually makes NO power connection between the mobo header and its fans, so it puts no load on the mobo header. But as I said, a Hub ONLY works if both the host header and all the fans involved are of the newer 4-pin design and the header is using the PWM Mode to put out its control signals.

You have a couple of details a bit wrong. On any mobo there are two types of fan control systems both very similar. In each case it actually is a TEMPERATURE control system that concentrates its work on a Temperature target at a particular sensor. In manipulates the speed of the fan attached to the header as the means to keep that sensor's reading on target at all times. So we call it a fan speed control system, but really it just manipulates that variable as a meas to achieve its real goal, temperature.

There is always a CPU_FAN header that uses only the temperature sensor built into the CPU chip itself as its guide. Some mobos also add extra headers like CPU_OPT, etc. that also use that same sensor. Then there are one or more (on your case, two) SYS_FAN or CHA_FAN headers that normally use a different sensor built into the mobo, and those headers are used to manage the case ventilation fans. Many mobos now also add one or more additional temperatures sensors on particular mobo heat sources and allow you to decide to use one of those instead of the "general purpose motherboard" sensor if you want to. Some of those also let you use the CPU internal sensor if you have a good reason. So, fans connected by whatever means to a SYS_FAN header are not totally devoted to cooling the CPU in any way, although they most certainly contribute to a supply of cool air inside the case that the real CPU cooling fan uses for its purposes.

No mobo has any good way to find out the temperature of any key heat sources on an added video card. Most video cards with fans do their own temperature control on-board by monitoring a sensor and controlling their fans. Of course, the source of air for this is the air in the case provided by the case fans, but there is no good way to link those case fans to the video card fans.

There ARE some exceptions to that last paragraph. There are a few mobo makers who also make video cards designed with a way to feed their own temperature sensor reading out on the PCIe bus, AND who also design their mobo bus to allow the BIOS to read that sensor and make it available for you to use to guide a case fan plugged into a SYS_FAN header. This is a non-standard feature and only works if you have a mobo and video card combo that are designed for this. IF you have that, you can arrange to have case fans that blow toward the video card controlled by the video card's on-board temperature sensor and thus ensure a good supply of outside air near that card.

 

[jwburks1976]

Interesting. I think I understand how a hub uses the PSU to power the fans, and the motherboard's fan header to send the signal.

What I still don't understand/know is: can fans of different sizes/speeds/etc. be used together on a hub, safely?

In my case, I'll have a freakshow display of varieties of fans. One 200mm in the front, one 140mm in the back for exhaust, two 140mms on the NH-D15, and perhaps four 120mms on top. Two of the 120mms will go into a Y-splitter and into one of the chassis headers, and the front, back, and top fans will all be connected to a hub going into the second chassis header. It worries me, a bit. Only because of the different sizes and rpms of the fans, but... I am thinking (hoping) that PWM signals send "percentage" signals, as in... use 30% speed, and they would all adjust accordingly. But I don't know. I have read conflicting information on this all over the internet and I still have no clear answer.

Even downloading and reading pdf instructions for all of the hubs I've been able to find don't explain this. It's omitted entirely. Very vexing.

 

[Paperdoc]

Your understanding is quite close, and no, there is NO danger in mixing fan sizes. There IS a problem if you try to mix 3-pin and 4-pin fans together on the same feed system, using either a Hub or a Splitter, because the method of controlling those two fan designs is different and requires different signals from the mobo header.

Start from here. We talk about Fan Speed Control. But the truth is the automatic control systems on a mobo are really TEMPERATURE control systems. In each case they monitor the actual reading of Temperature from a sensor and manipulate the speed of their fan to make sure that measured temperature stays on target. Fan speed is NOT its aim, it is only the variable it manipulates to achieve its aim. And so, it does not even care about or look at the fan speed value in doing its work. On a 3-pin fan it changes the speed by changing the voltage supplied to the fan on Pin #2. For a 4-pin fan that voltage is fixed at a full 12 VDC all the time, and speed is altered by supplying the new PWM signal to the fan, where a chip uses it to modify the current flow through the windings. But irrespective of the method, the header simply makes the fan run at whatever it takes to get that measured temperature on target.

By the way, the fan's speed signal IS used by the mobo header for a different purpose - detecting fan failure. That is how it can warn you that a fan has failed.

Now, if you mix different fans (but all one type, let's say 4-pin) together using a Hub or a Splitter to a single fan header, all the fans receive exactly the same signals. BUT each different fan model will produce a different speed as a result. This does NOT matter at all, because the whole aim of the system is to produce enough AIR FLOW in TOTAL to cool the system and get the measured temperature at the sensor on target.