Question Do I need a PWM Controller/header in order for my ML140 and ML120 fans to work? My motherboard model is Gigabyte z170m-d3h


Feb 18, 2017
Hi guys i just wanted to know if I will need a PWM controller for this motherboard or can I run the ML140 and ML120 fans and have Magnetic Levitation work even when connecting straight to the Motherboard?
Yes, Mag Lev feature does NOT require special electrical connections.

Your mobo has three SYS_FAN headers with 4 pins each. However, the manual's labels for those headers (see p. 15) leave me to believe they are actually operated as the older Voltage Control Mode headers. This will have virtually NO impact on your fans. Those 4-pin PWM type fans have a backwards compatibility feature in their design so that the WILL operate properly with speed controlled by this method. However, it does mean that you cannot use a HUB to connect several fans to a single SYS_FAN header. If you need to connect many fans, you CAN use Splitters to do that, but if you have only three or less case ventilation fans that won't be necessary. If you have lots of fans, post back here how many and we can advise on how to identify a Splitter and NOT a Hub.
Makers use confusing names for these things, so I'll offer a way to distinguish. A SPLITTER simply connects all of its fans in parallel to the mobo header pins. It has TWO types of "arms". There is one "arm" that ends in a female (with holes) fan connector that plugs into a mobo fan header. There are two or more output "arms", each with male (pins) connectors for plugging in your fans. There are NO other types of connecting "arms". (Note that some Splitters actually look like little printed circuit boards, but they still have only those two types of connections.) You need to understand a couple small points when using these.
  1. A mobo header can deal with the speed signal sent back to it from only ONE fan. So any Splitter will send back that signal from only one of its fans, and ignore all the others. In a Splitter that looks like groups of cable arms, the most common way to do that is to include Pin #3 in only ONE output arm, and omit it in all others. This has no impact on ability to control the fan speeds. It does mean, however, that the mobo header cannot monitor ALL of the fans on the Splitter for FAILURE because it sees the speed signal of only one. And of course YOU will only see the speed of one of those fans in BIOS displays.
  2. The only source of power for the fans on a Splitter is from the mobo header, and that header normally has a limit of max 1.0 A current to all its fans. So you must add up all the max current specs for the fans you connect to the Splitter and its header and be sure you don't exceed that. In your case, OP, the fans are spec'd to have max current consumption each of 0.22 A, so even four of them connected to one header would not pull over 0.88 A and fit within that limit.
A HUB is a different device that has those two types or "arms", PLUS a third "arm" that must connect to either a SATA or a 4-pin Molex power output from the PSU. This device gets all fan power from the PSU that way and none from the mobo header, so it avoids the current limit issue. However, it ONLY works if you are using it with 4-pin fans (you are, OP), AND if the mobo header is using the newer PWM Mode to control fans, thus supplying the PWM signal on Pin #4 that the Hub MUST have. In your case, as I said in the previous post, the manual indicates that the SYS_FAN headers do NOT send out the PWM signal and use only the older Voltage Control Mode (aka DC Mode) for control. So you can NOT use a HUB.

Here is an example of a 4-pin fan Splitter with two 6" long output arms fan splitter&cm_re=Coboc_fan_splitter-_-12-423-160-_-Product

A similar product has 12" long arms if you need that. And here's a different Splitter with 4 outputs that looks like a circuit board fan splitter&cm_re=Coboc_fan_splitter-_-82-422-016-_-Product

It has one output labelled for the CPU fan, but do NOT plug your CPU fan in there. That is simply the only output port that sends its fan's speed signal back to the host mobo header.

OP, with four fans and three SYS_FAN headers, you could use just one Splitter to combine two fans onto one header, with single fans on the other two. Or you could use more Splitter(s) and fewer headers IF you have some reason for that, like neater cable routing.