Question How to get case fans to turn off when put PC to sleep ?

worstalentscout

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Nov 1, 2016
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hi

does case fans with 3-pin or 4-pin make a difference ?....

should the fans be connected to motherboard or PSU so they will turn off when PC is put to sleep ?

i've read people say their fans connected to PSU will turn off when PC goes to sleep.......are the fans spinning at full speed when PC is active when connected to PSU ?
 

geofelt

Titan
4 pin fans can be either molex or pwm.
Molex (white connector) is connected directly to the psu.
When powered on, it will run at max speed.
I think it will stop when sleeping.

3 pin fans are voltage controlled and go into a cpu header.
4 pin pwm fans are pulse rate controlled and will also go into the motherbard header where they can be speed controlled by the bios.
 
does case fans with 3-pin or 4-pin make a difference ?....
Yes. 3-pin fans have a narrower range of control vs 4-pin ones. The last time I've used 3-pin fans, they could only go down to about 50%. 4-pin ones can go down to about 20% (at least from what my motherboard can handle)

should the fans be connected to motherboard or PSU so they will turn off when PC is put to sleep ?
It doesn't matter. The PSU for all practical purposes isn't delivering power to anything its connected to until it turns on.

i've read people say their fans connected to PSU will turn off when PC goes to sleep.......are the fans spinning at full speed when PC is active when connected to PSU ?
If you directly connect it to the PSU, yes. If you connect it to the motherboard, it depends on what the motherboard is doing.
 

worstalentscout

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Nov 1, 2016
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4 pin fans can be either molex or pwm.
Molex (white connector) is connected directly to the psu.
When powered on, it will run at max speed.
I think it will stop when sleeping.

3 pin fans are voltage controlled and go into a cpu header.
4 pin pwm fans are pulse rate controlled and will also go into the motherbard header where they can be speed controlled by the bios.

ok, many thanks
 

worstalentscout

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Nov 1, 2016
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Yes. 3-pin fans have a narrower range of control vs 4-pin ones. The last time I've used 3-pin fans, they could only go down to about 50%. 4-pin ones can go down to about 20% (at least from what my motherboard can handle)


It doesn't matter. The PSU for all practical purposes isn't delivering power to anything its connected to until it turns on.


If you directly connect it to the PSU, yes. If you connect it to the motherboard, it depends on what the motherboard is doing.

so if PC is in normal use and 3-pin fans are connected to PSU.........fans will be at full speed ?

but when PC is at sleep....PSU still powering RAM.......the fans connected to PSU will also turn off ?

so overall, 3 or 4 pin......better to put fans to motherboard for better control then ?
 
so if PC is in normal use and 3-pin fans are connected to PSU.........fans will be at full speed ?
If you're using some adapter to plug in a 3-pin fan into a PSU (because PSUs don't normally come with fan headers), then yes.

but when PC is at sleep....PSU still powering RAM.......the fans connected to PSU will also turn off ?
Yes

so overall, 3 or 4 pin......better to put fans to motherboard for better control then ?
In either case, it's better to use the motherboard or a dedicated fan controller.
 

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