Running 80mm case fan off the CPU fan?

Alcpone · Feb 13, 2013

For some reason I can't control the speed of my case fan that is connectecd directly to the sys fan on my mobo, it is at full speed all the time and I cant control it with speed fan or the like, can I splice it into the cpu fan so it speeds up and slows down with that?

Jetster · Feb 13, 2013

Did you try the BIOS to set the speed? Its probably not thermally controlled but most MB have a speed setting. Did you install cool and quite?

xvi · Feb 13, 2013

I have NEVER had SpeedFan work for me. Try downloading AMD Overdrive.

I would be careful with how much amperage you pull off of one fan header. If you don't want it running at full speed, I would do one of three things. One, buy/make/find an adapter to run the fan off of 5v from a 4-pin molex connector. Two, buy a fan controller. Three, buy a lower power fan to replace it.

If you do try to splice it in to the CPU fan, make sure to omit the yellow wire. That's the tach.

brandonwh64 · Feb 13, 2013

Speedfan is a dying piece of software. I have never had it work for me either, even on P4 machines. The best thing for fan control is a bay controller. Yes the CPU fan header will work but what do you have your CPU cooler plugged into?

newtekie1 · Feb 13, 2013

Your CPU fan is likely speed controlled via PWM(4-wires) while your case fan is probably not PWM controllable(3-wires). So even if you did splice them together, the case fan would still likely run at 100% all the time.

Also, the SYS_FAN1 header on your motherboard is a PWM header as well, so if you have 3-pin fan connected to it the header won't be able to control the speed. So the solution would be to buy a 4-pin PWM Case fan to replace the current 80mm case fan.

This should do the trick: GELID Solutions FN-PX08-20 Case Fan - Newegg.com

Alcpone · Feb 13, 2013

Ok thanks for the replies. It is only a 3 wire fan and the sys fan has only 3 pins so not sure if the sys fan does have pwm or not? I thought the the speed was governed by home much power the mobo was giving it?

Jstn7477 · Feb 13, 2013

The board has 4 headers from what I see: CPU_FAN (PWM), PWR_FAN (DC, top right, probably fixed at 100%), SYS_FAN (PWM, bottom right, probably adjustable) and SYS_FAN2 (DC, bottom edge, likely fixed at 100%). Most boards under $100 only have one or two controllable headers, and PWR_FAN is usually fixed at 12v on most boards.

Alcpone · Feb 13, 2013

I will try a different header. Cheers

Alcpone · Feb 15, 2013

Turns out I had it plugged into the pwr fan header, oops. Tried in the sys fan header and it works a treat, only problem I have is it is too short to reach, typical. I will have to get some wire or splice it into the cpu fan.

AsRock · Feb 15, 2013

Make sure it's not a very high ampage fan too like some delta fans are as a lot of mobo headers only can take so much drain on them.

Alcpone · Feb 15, 2013

All sorted now. Thanks

cadaveca · Feb 15, 2013

AsRock said:
Make sure it's not a very high ampage fan too like some delta fans are as a lot of mobo headers only can take so much drain on them.

1A total or less, depending on board model.

de.das.dude · Feb 15, 2013

speedfan sux

the best way to control is to get a cheap controller

Geofrancis · Feb 19, 2013

If you get a 4 pin PWM case fan you can attach the 4th PWM wire to the CPU fans PWM wire and it will be controlled with the CPU even with the fan plugged onto a 3 pin header.

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Running 80mm case fan off the CPU fan?

Alcpone

Jetster

xvi

brandonwh64

Addicted to Bacon and StarCrunches!!!

newtekie1

Semi-Retired Folder

Alcpone

Jstn7477

Alcpone

Alcpone

AsRock

TPU addict

Alcpone

cadaveca

My name is Dave

de.das.dude

Pro Indian Modder

Geofrancis

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