Question Connecting 2-pin Fan to 4-pin PWM Fan header

Mar 21, 2019
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I need to install a extra chassis Fan to my Mini PC to reduce temperature. motherboard have 4-Pin PWR Fan header and Mini PC chassis provide enough space to hold 20mm x 20mm x 7mm Fan. My problem is 20mm x 20mm x 7mm Fan are only manufactured with 2-Pin so If I create a 4-Pin to 2-Pin converter is it OK to connect 2-Pin Fan to 4-Pin PWM header? Is there any hazard I should worry about? Any advice and guide is appreciated. thank you

https://files.fm/u/p5gj7xf6
 
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Yes, it will run full speed. But you also will need to make the right connections, likely needing some custom wiring soldering. I expect the connector on the end of the two wires from the fan motor is not the common 3-hole or 4-hole female fan connector that would fit onto the pins of the mobo header. However, it might fit anyway as long as you make sure to connect the right way around. Whether this works, or whether you have to custom fit some other way, here's how.

On the Mobo HEADER with 4 pins there is a plastic "tongue" sticking up beside the first three pins - Pin #4 is beyond the tongue. Pin #1 is the Ground pin, and Pin #2 is the +12 VDC power supply. On the FAN, most commonly the BLACK wire is for Ground, and the RED wire is +12 VDC. Just connect that way and it will work. NOTE one thing. The mobo header normally checks the fan's speed signal to ensure that it is running, and will send out warning messages if it fails. Your fan has no speed signal wire to header Pin #3 so it cannot send that signal to the mobo. Thus the header will tell you the fan has failed. In BIOS Setup, see if you can disable the warning messages from that header to stop the annoyance.

FURTHER, how do you plan to connect to the mobo header? Do you not have another fan plugged in there already? If you do, are you going to use a Splitter to connect two fans to the header? IF you do that, don't worry about the speed signal problem. A Splitter will only send to its mobo header the speed of ONE of its fans, and the output connectors of the Splitter are different for this reason. ONE will be identified as the only output that sends back its fan's speed signal. Just ensure that the REGULAR fan is plugged into that output, and the new fan into a different one.
 
Reactions: Dileepamax
Mar 21, 2019
3
0
10
0
Yes, it will run full speed. But you also will need to make the right connections, likely needing some custom wiring soldering. I expect the connector on the end of the two wires from the fan motor is not the common 3-hole or 4-hole female fan connector that would fit onto the pins of the mobo header. However, it might fit anyway as long as you make sure to connect the right way around. Whether this works, or whether you have to custom fit some other way, here's how.

On the Mobo HEADER with 4 pins there is a plastic "tongue" sticking up beside the first three pins - Pin #4 is beyond the tongue. Pin #1 is the Ground pin, and Pin #2 is the +12 VDC power supply. On the FAN, most commonly the BLACK wire is for Ground, and the RED wire is +12 VDC. Just connect that way and it will work. NOTE one thing. The mobo header normally checks the fan's speed signal to ensure that it is running, and will send out warning messages if it fails. Your fan has no speed signal wire to header Pin #3 so it cannot send that signal to the mobo. Thus the header will tell you the fan has failed. In BIOS Setup, see if you can disable the warning messages from that header to stop the annoyance.

FURTHER, how do you plan to connect to the mobo header? Do you not have another fan plugged in there already? If you do, are you going to use a Splitter to connect two fans to the header? IF you do that, don't worry about the speed signal problem. A Splitter will only send to its mobo header the speed of ONE of its fans, and the output connectors of the Splitter are different for this reason. ONE will be identified as the only output that sends back its fan's speed signal. Just ensure that the REGULAR fan is plugged into that output, and the new fan into a different one.
Thank you @Paperdoc I attached a two pictures of the setup the 4-pin PWR port and the fan converter I create

https://files.fm/u/u22nt2mv
 
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The link only showed one photo - the power port. That's an unusual thing. It appears to be a mobo "header" version of a 4-pin Molex power MALE connector, except that a normal male Molex has ROUND pins, not small square ones. Now, IF that port actually has +12 VDC and Ground on the two left-most pins, then you can use them to power that fan. This would be similar to using a PSU Molex output instead of a mobo fan header, and the fan will always run full speed, which is OK with you. Regarding polarity, most times the RED wire on a fan is for the +12 VDC connection. But if you get it backwards, there will not be any bad damage. The fan might just run backwards, or not at all. BEFORE you install it, look closely at the fan frame for markings. Many case fans come with two arrows on the outside. One shows the rotation direction. The other points through the fan to show air flow direction. If you find those, just check that the fan it blowing as the arrows say when it it powered on.
 
Reactions: Dileepamax

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