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Akasa 5-way PWM Splitter not functioning correctly

post #1 of 6
Thread Starter 
Hi guys,

so I just installed my new fans in the case. I connected them to my SYS2_FAN PWM header using the Akasa 5-way pwm splitter. The fans are Akasa Viper 140mm. This MoBo header works fine when one fan is connected (I use SpeedFan to regulate the fans) but when I use the splitter, all the fans run at full speed no matter what I do.

I tried connecting the PWM splitter to the CPU_FAN header and there it works just fine. My MoBo is Gigabyte GA-P55A-UD4 and it has 2 PWM headers - the CPU_FAN and SYS2_FAN.

Why is this working on one PWM header and not the other? Any ideas to solve the problem?

Thank you,

Jure
post #2 of 6
I had the same issue with a 3-way akasa splitter a little while ago.
Quote:
I've now figured out what was going on with the PWM splitter! Turns out that the cable was fine.
It's my bloody Chassis2 header being a dick. Basically, it's a 4pin header pretending to be a full on PWM header.

The Chassis2 header will control 3 or 4pin fans but lacks actual PWM functionality. So when the splitter is connected to it, only RPM and PWM signals go in and out (as they're the only two wires on the end of the splitter's mobo connector).
Since there is no working PWM pin on that header, the fan will run at full pelt with no control using the splitter.

I swapped the CPU fans (built in splitter) to Chassis2 header and put the 3-way split case fans onto the CPU header and now have full fan control since the 2 120mm cooler fans are connected with a fully wired plug to Chassis2 which only needs 3 pins to work.

Hope that helps, or even makes sense smile.gif

Btw, my board specs say that the Cha2 header does have pwm, but I dunno... It does control PWM fans, but it also controls 3pin fans too. The fact that it won't control them when only rpm and pwm cables are connected to it says otherwise.
Edited by Speshy - 8/27/12 at 5:10pm
    
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CPUMotherboardGraphicsRAM
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OCZ Agility 3 120Gb Western Digital Blue 500Gb Koolance 380I CPU Block EK FC7970 GPU Block 
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post #3 of 6
Are you sure that your motherboard supports PWM on SYS_FAN2? In the pinout description listed in the user manual, pin 4 is "reserved" for SYS_FAN2 whereas it is "Speed Control" for CPU_FAN.
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post #4 of 6
Sys_fan2 header doesn't output PWM signal on any of my Gigabyte boards even though it is a 4-pin header, it does only voltage control.
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post #5 of 6
What Speshy, Kota and mm67 said.

All my fans are controlled by CPU_Fan header feeding 2 PWM splitters wink.gif
post #6 of 6
Thread Starter 
Thank you guys, I did exactly that - connected the splitter to the CPU_FAN header and the CPU fan to SYS_FAN2 header and everything works perfectly now.

I don't understand why or how the SYS_FAN2 header only imitates a PWM. I can set the speed in increments of a 1%, I shouldn't be able to do that with voltage control. Meh.

Thanks for the help!

+rep

J
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