[SOLVED] Fan hub

[Yuumiis]

hi, i recently wanted to buy a fan hub as i have 3 case fans but only 1 is working as i dont have enough headers, so i was thinking when i connect fan hub to psu and fans to the fan hub, and then to the header, won't it be a problem with having too much power to go to the fan header?? or is it just gonna take info about speed and etc in the fan header

 

[lvt]

Fan hubs usually uses power from a Molex or SATA power cable.

 

[hotaru.hino]

In addition to the above, fan hubs, if they more or less "dumb" devices, will use the same speed from the one header. Also this means you cannot mix PWM and voltage controlled fans. Or at least, one or the other will operate at 100% all the time.

If you want something with more smarts in it, NZXT and Cosair make fan hubs you can control via software.

 

[Paperdoc]

You do not have to worry about your basic question. A fan HUB gets all the power for its fans from the PSU connection and has NO connection to the power output pin (#2) of the mobo header. So it cannot force any power back to the header. What it DOES do with the cable to the mobo header is get the PWM control signal from Pin #4, and return to the header on Pin #3 the speed signal from ONE of its fans so the header can display that speed. The header cannot deal with more than one speed signal, so the Hub will only send back one. You have to assume the other fans on the Hub are doing something very similar.

Almost all HUBs have a couple of limits on what it can do. It can only supply power to its fans at a fixed 12 VDC, and it can send to all its fans the Speed Control (PWM) signal from the host header. This means it can ONLY be used with the new 4-pin PWM fan type, AND it means that the host header MUST be configured to use the PWM Mode so that it sends out the PWM signal needed. A 4-pin fan has a small chip that uses the PWM signal to modify the power flow from the fixed 12 VDC supply line though the motor to change the speed. An older 3-pin fan's speed can NOT be controlled this way (it has no chip), so when you plug one of those into a normal HUB, that 3-pin fan always runs full speed. The ONLY way to control the speed of older 3-pn fans is to change the VOLTAGE sent to it on Pin #2, and only a mobo header operating in the older Voltage Control Mode (aka DC Mode) can do that. Then you must use a SPLITTER, not a Hub. A Splitter is different because it does NOT take any power from the PSU directly - it has NO cable for that. It gets all fan power solely from the mobo header.