[SOLVED] Should I use the Fractal Design fan hub?

[GregP74]

My Meshify S2 case arrived yesterday. It's got a fan hub on the back and I'm not sure if I want to use it or not.

I know for sure I'm not going to do what the manual says and let the cpu_fan header control all of them.

I plan on running the 2 fans for my CPU cooler off the CPU_Fan header with a splitter. I don't see any benefit to running the second one on CPU_OPT.

My bigger dilemma is what to do with the case fans. (2 input on the front, and exhaust on the back.) I'm a Noctua nerd and I've got some NF-14As on the way but they won't be here til the end of the week. In the mean time I'll be using the factory 3 pin fans. (I didn't even know 3 pin ones were still a thing. I figured they were all 4 pin PWM these days.)

The simplest thing to do would be just plug the hub into the CHA_FAN1 header and let it run all of them. Would I be better off running the exhaust fan off one and the input fans off another? Or giving myself more flexibility and running the two inputs separately from each other?

 

[Paperdoc]

Especially if you are going to use the 3-pin fans supplied with the case, use the Hub, but not exactly as instructed. The advantage of the Hub IF it is designed properly is that it takes the PWM signal from a mobo header and provides that to its 4-pin fans directly as any normal Hub would. But it ALSO SHOULD be converting those signals into the older Voltage Control Mode for its four 3-pin fan output ports so that they also are under speed control. (Without that conversion, the 3-pin fans would run full speed all the time,)

The deviation I suggest is NOT to connect the Hub's fan header input port to the mobo CPU_FAN header - leave that CPU_FAN and CPU_OPT combo to your CPU cooling uses only. The cable from Hub to mobo header should go to a mobo CHA_FAN or SYS_FAN header so that the case ventilation fans are guided by the temperature sensor on the mobo, not by the one inside the CPU chip. Just make sure that ONE of your case fans is plugged into the Hub output port marked for the CPU cooler. That is the only Hub output that can return its fan's speed to the host header.

One small technical detail is missing here and not provided by the makers. The PWM Noctua fans you anticipate soon are best controlled using real PWM Mode, but like all of this fan design, they CAN have their speed controlled by the older Voltage Control Mode. Thus they WILL be speed-controlled no matter which type of control signals they are sent, although technically PWM is better for them. Now, most Hubs will simply distribute the PWM signal from the host header, and that gives any PWM fan exactly what it needs. This particular Hub appears to convert from PWM to Voltage Control Mode for use by the four 3-pin output ports. We do not know if the Hub's three 4-pin ports also are being fed those same converted signals, or are getting the original mobo PWM signals. You can test that, though, if you have a voltmeter. Look at the 4-pin ports. There is a plastic "tongue" sticking out next to Pins 1-3, and Pin 4 is beyond the tongue. The power supply is on Pins 1 and 2, Pin #1 (Ground) being on the outer end. (The 3-pin ports are wired similarly.) When operating, Pin #2 of a PWM header will always be 12 VDC no matter what fan speed is required. On a Voltage Control header (3-pin), Pin #2 will have a LOWER voltage when the fan is supposed to run slower. So just check what voltage is on Pin #2 versus Pin #1 when the system is running. If it is always 12 VDC, then the port IS using true PWM Mode ideal for 4-pin fans.

 

[Paperdoc]

Thanks for Best Solution.