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GA-EP45-UD3P sys_fan 2 speed to slow

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April 16, 2009 4:56:36 PM

I have a question about system fan 2 speed on GA-EP45-UD3P ver 1.0 (bios F8)

I recently installed 2 PWM Arctic Cooling fans. Rear fan 120mm runs of the cpu header and is controllered by CPU PWM and it works well, but front fan 92mm I connected to header sys_fan2 (4 pins as well), and the fan spins very slow only between 200-300rpm. Is there any way to fix this?
I know all fans are good because I can run all 3 fans of the cpu header and all fans speeds are in range of 500-1500, and I can control their speed with Easy Tune 6.
Header sys_fan2 runs the fan only at 195-300 rpm.
My bios version is F8 and mobo ver 1.0

Any suggestions?
Tks.

Paul.
April 16, 2009 5:41:59 PM

FYI...just add to my post. My 120mm rear fan won't even spin on sys_fan2 header.
Is this a UDF (unintentional design feature) on UD3P/UD3R mobos?
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June 23, 2009 3:04:49 PM

Hi, i am not gonna be of much help here but i seem to have the same problem

I bought a new PSU a "be quiet! 650w" and it had four seperate fan connectors which the psu is supposed to control the fans according to how hot the PSU is??? anyway it had (what it says in the manual) a "RPM" fan thing which i read on a forum to plug into the power fan header. when i did this all my fans running slow and the led's dimmed

anyway i got my pop to re-qire some molex's cos i thort well i'd rather just have them running full speed all the time then i know where i am! by the time he came back i sort of sorted the problem...

my case is a cm690 so i have two fans on the top, now i just plugged both of the connectors in the mobo (same as yours btw) and then looked on easytune and the fans were running at full speed. so my only suggestion is maybe if you tried plugging in another fan at sys_1?

Sorry its not much help but, im looking for the same answer i just got a fan controller... so plugged my bottom fan in sys_2 and now its running slower again but not as slow as your one.

Rob
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June 23, 2009 3:31:26 PM

From GB tech:
Quote:
SYS_FAN2 connector needs any fan, with three or four wires (don't care) since the speed is controlled via on-board PWM controller that supply pulse-width-modulated 12v for the fan via pin 2. So, if using a four wire fan, its internal PWM is locked to full speed (this explain that fixed 5v on pin 4). This time, the mobo senses the North Bridge temperature and will increase or decrease the speed of the fan connected in this socket. Feedback is sent to pin 3 for BIOS alarm purposes.

Though it seems like it should be 'fool-proof', this method of operation doesn't agree with some fans' internal switching setup... If that's your experience, it's pretty easy to 'piggy-back' fans off any header you please - just don't exceed five fans per header:
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September 19, 2009 4:43:47 AM

bilbat said:
From GB tech:
Quote:
SYS_FAN2 connector needs any fan, with three or four wires (don't care) since the speed is controlled via on-board PWM controller that supply pulse-width-modulated 12v for the fan via pin 2. So, if using a four wire fan, its internal PWM is locked to full speed (this explain that fixed 5v on pin 4). This time, the mobo senses the North Bridge temperature and will increase or decrease the speed of the fan connected in this socket. Feedback is sent to pin 3 for BIOS alarm purposes.

Though it seems like it should be 'fool-proof', this method of operation doesn't agree with some fans' internal switching setup... If that's your experience, it's pretty easy to 'piggy-back' fans off any header you please - just don't exceed five fans per header:
http://img265.imageshack.us/img265/5969/fanhdr1.jpg


Billbat, thanks for the diagram. I am confused by the rheostat on SYSFAN_2. Are you suggesting I cut the middle wire of the fan and install a rheostat to make this piggy back work? I am not an engineer so looking at this diagram I see myself simply "cutting and pasting wires" with tape according to your diagram. And by bridging SYSFAN_1 and SYSFAN_2 are you saying that East Tune 6 can then controll the fan speeds and will both fans run at the same speed and be reported in the gigabyte utility ET6?

On the toher circuit I am bridging the CPU and PWR fan and here again the speed will be controlled by ET? In this case will the PWR Fan run at the same speed as the CPU Fan. This is very cool. I don't see a rheostat here so that is what is also confusing me. Bottomline can you please spell out what we are achieving by this diagram? I think it is allowing ET6 to cntrol all fans. Many thanks.

I myself connected to SYSFAN_1 at a screeching 2500 rpm the case fan. No control. However SYSFAN_2 RPM is a constant 1500 RPM and I think not being controlled either. I have a EP45-UD3p mobo i am now building. Above refers to UD3R. Thanks. I should have gone to engineering school:) 
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a b à CPUs
a c 177 V Motherboard
September 19, 2009 10:54:47 PM

The trim pot is not necessary - I just use it as smaller fans run faster at the same voltage, and I didn't need that much air on my southbridge. The idea is, that if you're happy with the speed you get from the CPU_FAN header, you can run a number of fans from it; if you look here:
http://www.arctic-cooling.com/catalog/product_info.php?...
you'll see that Arctic actually sells fan with these 'splitter' cabes already on them; they call it PST - PWM Sharing Technology, but it's just the PWM splitter (right-hand, four wire one) in the diagram... The hardest part is getting hold of PWM (four pin) plugs and headers!
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