Where do PWM cables go?

[noahmorgans]

I am planning on hooking my my case fans to PWM but don't know where I'm supposed to plug it in. Do I plug it into the motherboard or the PSU?

 

[DRagor]

Motherboard. If you want to use PWM to control fan speed, you have to connect them to 4-pin fan headers on motherboard that support PWM (because some motherboards have 4-pin headers that are 'fake' and actually do not support PWM).

 

[Brawly44]

PWM stands for "Pulse Width Modulation", this allows the motherboard bios to control your fan speeds based upon temperature variations. The PWM connector at the end of the fan cable is plugged onto the PWM headers located directly to the motherboard. The PWM connector will have 4 pins in the header. DO NOT connect your fan directly to the PSU. You might reference your owners manual to find all of the fan headers on your motherboard, but in most cases you can find them visually, just look for the 4 pin header connections. I hope this helps.

 

[noahmorgans]

Motherboard. If you want to use PWM to control fan speed, you have to connect them to 4-pin fan headers on motherboard that support PWM (because some motherboards have 4-pin headers that are 'fake' and actually do not support PWM).

https://www.newegg.com/Product/Product.aspx?Item=N82E16813130993&ignorebbr=1&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-PCPartPicker,%20LLC-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=

Does this motherboard have fake 4-pins?

And another thing is I have 5 fans (1 comes with the case, 4 I bought) and my motherboard only has 4-pin slots. Should I plug one into the PSU somehow or is there a solution to this?

 

[Brawly44]

Motherboard. If you want to use PWM to control fan speed, you have to connect them to 4-pin fan headers on motherboard that support PWM (because some motherboards have 4-pin headers that are 'fake' and actually do not support PWM).

https://www.newegg.com/Product/Product.aspx?Item=N82E16813130993&ignorebbr=1&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-PCPartPicker,%20LLC-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=

Does this motherboard have fake 4-pins?

And another thing is I have 5 fans (1 comes with the case, 4 I bought) and my motherboard only has 4-pin slots. Should I plug one into the PSU somehow or is there a solution to this?

 

[Brawly44]

I think your best bet is to pick up a fan cable splitter. This way you can connect 2 fans to the splitter and regulate the both of them off of 1 PWM header. I would not recommend connecting your case fan directly to the PSU. Also, there would be no way to regulate the speed of a fan connected directly to your Power Supply.

 

[Karadjgne]

Buy enough pwm splitter cables to keep the fans in pairs. I'm assuming you have 2x fans in front, 2x fans at top and 1x rear. Use 1x pwm splitter for both front fans, 1x splitter for both top fans and plug the rear exhaust to the mobo direct. This keeps local fans spinning at the same speeds

 

[noahmorgans]

Buy enough pwm splitter cables to keep the fans in pairs. I'm assuming you have 2x fans in front, 2x fans at top and 1x rear. Use 1x pwm splitter for both front fans, 1x splitter for both top fans and plug the rear exhaust to the mobo direct. This keeps local fans spinning at the same speeds

I'm planning on doing 3 intake at the front, 1 exhaust on top and back since I heard it's better to keep the pressure positive. I found like a $3 3 part fan splitter that I plan on using for the front and probably just leaving the other two on their own. Do you think I will need to buy a PWM cable for the case fan or will it come with it?

 

[Karadjgne]

Fans come with a length of wire already attached to the motor that has a connector on it. Some fans are 3pin which is analog, controlled by voltage levels, and some fans are 4pin pwm which are a constant 12v, but speed regulated by having that 12v turned on/off so the fan is in a constant state of trying to spin at maximum and not getting there.

So when you get your splitter for the 3x front fans, you'll need to make sure of 2 things. First and foremost you need to look at the fans themselves. You need to know the amperage or wattage they operate on. The motherboard header is good for @0.8A roughly, absolutely max at 1A. With 3 fans this is important because it would be best if the fans operate @0.2A or 3w or less.
If all 3x fans add up to more than 0.8A or @ 9-10w, then you'll need to revise your splitter and instead of a direct pwm splitter, use a powered pwm splitter. These splitters do not use power from the fan header, they use power directly from the psu by Sata, molex, or even USB (via mobo port) but the tachometer is controlled by the motherboard. So then you can use any amount of fans and not hurt the motherboard as power is from the psu.

So. Make sure your splitter is 4pin pwm, not 3pin and check the power needs of the 3x fans to see if you need a powered splitter or not.

Simple, eh?

 

[noahmorgans]

Fans come with a length of wire already attached to the motor that has a connector on it. Some fans are 3pin which is analog, controlled by voltage levels, and some fans are 4pin pwm which are a constant 12v, but speed regulated by having that 12v turned on/off so the fan is in a constant state of trying to spin at maximum and not getting there.

So when you get your splitter for the 3x front fans, you'll need to make sure of 2 things. First and foremost you need to look at the fans themselves. You need to know the amperage or wattage they operate on. The motherboard header is good for @0.8A roughly, absolutely max at 1A. With 3 fans this is important because it would be best if the fans operate @0.2A or 3w or less.
If all 3x fans add up to more than 0.8A or @ 9-10w, then you'll need to revise your splitter and instead of a direct pwm splitter, use a powered pwm splitter. These splitters do not use power from the fan header, they use power directly from the psu by Sata, molex, or even USB (via mobo port) but the tachometer is controlled by the motherboard. So then you can use any amount of fans and not hurt the motherboard as power is from the psu.

So. Make sure your splitter is 4pin pwm, not 3pin and check the power needs of the 3x fans to see if you need a powered splitter or not.

Simple, eh?

I'm using the be quiet! Pure Wings 2 which only use 0.09A per fan so I will have plenty of room there. Thank you for your help.

 

[Karadjgne]

Perfect. A plain 3-way pwm splitter will work fine then. Hook all 3x fans to the ends, and the header to one of the sys_fan headers. The exhausts each get their own header directly. You can control all 3 by bios, SpeedFan or mobo software.

 

[DRagor]

https://www.newegg.com/Product/Product.aspx?Item=N82E16813130993&ignorebbr=1&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-PCPartPicker,%20LLC-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=

Does this motherboard have fake 4-pins?

All headers on this board can support PWM fans. Note however, that all headers marked as SYS_FAN are set to DC mode on default, so if you want to use PWM fans on them, you will have to change that in BIOS.
Also, while the board has only 4 system fan headers, it also has pump header, which also can be used for normal fan (and is set to PWM mode by default), so you don't need any splitters or hubs, as you can connect all 5 fans directly to headers. See motherboard manual page 32 for instruction on how to change header to PWM mode.

 

[Karadjgne]

You could have 1x fan per header, but that creates issues. First, the headers are spread around the board, requiring the use of extensions to fit all the fan placements, basically a wiring mess. Second, the fans will all respond differently as they don't all access the same address. Some will use one sensor, some another. So depending on exactly where the sensor is located, you'll see 1 intake fan spin much faster than the other two etc. Not only does this look wierd, but the broadcast exhaust from that fan is cone shaped, and will smother the cone from a less powerful source, like you pushing between two ppl instead of walking side by side.

Much better off keeping all 3 of the intakes on one header, so all 3 act like a single giant sized fan. The two exhausts can be separate as there's possibly a need to reduce top exhaust or increase rear exhaust or both at the same time.

 

[DRagor]

. Some will use one sensor, some another. So depending on exactly where the sensor is located, you'll see 1 intake fan spin much faster than the other two etc.

This is were Gigabyte boards rock - you can set the temp sensor for each fan how you like. You can even set all fans respond to single sensor.
But in case of OP motherboard, it does not matter at all, as this board seemingly has only one temp sensor.