fan splitter runs fans at max?

D1craig

D1craig

D1craig

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28 Aug 2014
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well i bought this fan splitter as my ITX motherboard only has 2 fan headers and once my pc is fully set up i will need atleast 5.

My basket at Overclockers UK:

Total: £4.79
(includes shipping: £0.00)
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the only thing i can think of is the fans i have plugged in atm are not the same, i only have 2. they will be changing to all be the same once i have finished my build. im not fussed about seeing the rpm of the fans, as it will onyl be showing me one as of now and they are not the same as i have said. one is 2200rpm and one is 750rpm. the 2200rpm sounds like its running at max as soon as the thing is turned on. its a vardar pwm fan.
 
Doyll recently explained to me how splitting a PWM signal between 2 different fans works.

https://forums.overclockers.co.uk/showthread.php?t=18708864

They will both run at a % of their max, so if set to 70%, the 2200rpm fan will run at 1550RPM, and the 750rpm fan will run at 525RPM (in theory at least, though if you check the graphs he posted, its not quite that simple)

Could you try running them at full speed to see how loud they are then? 2200RPM is pretty damn fast, you might be surprised how much noise that makes.

Its probably going to be difficult to have the 750RPM fan doing anything particularly worthwhile while sharing the same PWM as the 2200RPM fan while keeping the 2200RPM fan at a decent noise level..
 
What do the fans sound like when plugged directly into the header? Do you have full control over them?
 
new boy said:
Doyll recently explained to me how splitting a PWM signal between 2 different fans works.

https://forums.overclockers.co.uk/showthread.php?t=18708864

They will both run at a % of their max, so if set to 70%, the 2200rpm fan will run at 1550RPM, and the 750rpm fan will run at 525RPM (in theory at least, though if you check the graphs he posted, its not quite that simple)

Could you try running them at full speed to see how loud they are then? 2200RPM is pretty damn fast, you might be surprised how much noise that makes.

Its probably going to be difficult to have the 750RPM fan doing anything particularly worthwhile while sharing the same PWM as the 2200RPM fan while keeping the 2200RPM fan at a decent noise level..
Click to expand...

i have tried them at full and silent and they sound exactly the same.

Bantu said:
What do the fans sound like when plugged directly into the header? Do you have full control over them?
Click to expand...

i didnt try this... i dont know why it slipped my mind lol. ill give it a go when my gpu block arrives. i think i never tried it because the only cpu cooler i have that fits is an aio block so needed to use one of the fan ports up with that.
 
D1craig said:
well i bought this fan splitter as my ITX motherboard only has 2 fan headers and once my pc is fully set up i will need atleast 5.

My basket at Overclockers UK:

Total: £4.79
(includes shipping: £0.00)
​


​

the only thing i can think of is the fans i have plugged in atm are not the same, i only have 2. they will be changing to all be the same once i have finished my build. im not fussed about seeing the rpm of the fans, as it will onyl be showing me one as of now and they are not the same as i have said. one is 2200rpm and one is 750rpm. the 2200rpm sounds like its running at max as soon as the thing is turned on. its a vardar pwm fan.
Click to expand...

i have used that spliter and it works fine, i ram it with different size and brand fans without a problem

HOWEVER when i used it with my MSI z77 gd65 the fans run at 100% and it turned out that just because a motherboard as a PWM fan header dose not mean it works like pwm. some motherboard still used voltage regulation instead of a PWM pulse to slow fans.

my GA-x99-ud5 also did this because it would not controle my pump via pwm but it did control 3 pin fans
 
would they still use this stype of BS marketing for the new z170 boards? my board is
GA-z170n-gaming5.

ill have to read the manual again
 
D1craig said:
would they still use this stype of BS marketing for the new z170 boards? my board is
GA-z170n-gaming5.

ill have to read the manual again
Click to expand...

YEP :D


just to cover the silly things here.
1 your using pwm fans?
2 the pwm cable on the motherboard plug go's to pin 4 right?
3 are you overclocking a none K cpu, the boys i3 6100 is overclocked and the board read the temp at 100c all the time and his nzxt grid+ runs fans at 100% because of this.
 
Last edited:
ErikN said:
You are probably trying to control PWM fans from the SYS_FAN header.

Only the CPU_FAN header is PWM, the other is outputting a constant +5V on the PWM header, which cause PWM fans to run at full speed.

See page 14 for reference (VCC is +5V):
http://download.gigabyte.eu/FileList/Manual/mb_manual_ga-z170n-gaming5_e.pdf
Click to expand...

this is probably what i have done.

one of my fans is pwm the other is 3 pin.

to plug the fans in the wrong way around - so the pwm pin is not on the pwm pin would require some force.

i was thinking maybe its the molex thing on the splitter that is making it run at max speed.

ill get around to swapping my fan and pump around then, always read that the pump should be on cpu fan header.

why do they add 4 pin headers if they are not pwm?
 
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