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my recent Noctua Y splitter/ULN cable confusion and Solution

post #1 of 3
Thread Starter 
Ok so, i recently got my system together

3930k
ASUSs abertooth x79
Corsair ax760
noctua's NFF 12's in every fan hole..


I had quite the head scratching dilemma on my hands.

When using the Y splitter to decrease the amount of chassis fan headers i take up, i would also put the ULN (ultra low noise) adapters on the single outlet part

my issue was that if i used the above combo, only 1 of the 2 fans would spin.
this was after testing every fan to see if they worked correctly. which they did

1 fan will work correctly with the ULNA adapter, but 2 with the splitter and ULN adapter wont.

my conclusion is that since the ULN adapter has to deal with 2 fans instead of just one it was only allowing barely enough juice to get both spinning

the solution to this is just use the extender not the ULN adapter at the end of the Y. these fans are quiet without the adapter, so its really not even needed, unless you just want a silent system


I hope this was semi-helpful as it caused me quite the headache after spending almost 30$/fan i was just baffled that it wont work like that.

It took some trial and error but i got it to work


FAN (cable extension
>
mobo
FAN

dont use the ULN adapters anywhere in the connections unless its only to 1 fan. otherwise 1 or both fans wont spin, they'll twitch but that's about it
post #2 of 3
That's a bit weird. If you were using the LNA that comes with the NF-F12 (NA-RC6) it's just a 81Ω resistor.

One 0.05A F12 gets ~9V sucking juice through that 81Ω LNA.

Two F12s (0.1A) should get ~7.2 volts, more than enough to spin as F12s start @ ~5.5V:


Perhaps some fan control software or BIOS setting was lowering the voltage at the mobo header below 12V?




For the record I've just tested two 0.09A NF-P12s with an Y splitter.

With a blue classic ULNA (81Ω) before the Y splitter, they get just ~5.4 volts and none of them even start (non-PWM P-12s need ~6.5V to spin):


With a black classic LNA (50Ω) two P12s (0.18A) get ~6.9V and both barely rotate very slowly.
HAL-9011
(14 items)
 
  
CPUMotherboardGraphicsRAM
Phenom II 960T X6 4.1GHz ASUS M4A89GTD Pro Radeon HD 6870 16 GB DDR3 1600MHz 8·8·8·24 
Hard DriveHard DriveHard DriveOptical Drive
OCZ Vertex 4 128GB OCZ Vertex 2 120GB WD Caviar Black 1TB LG DVD-RW 
CoolingCoolingOSOS
Noctua NH-D14 Accelero S1 R.2 + 2x NF-F12 Se7en x64 Se7en x32 
PowerCase
Antec TP-650W CM HAF 912 + 
  hide details  
Reply
HAL-9011
(14 items)
 
  
CPUMotherboardGraphicsRAM
Phenom II 960T X6 4.1GHz ASUS M4A89GTD Pro Radeon HD 6870 16 GB DDR3 1600MHz 8·8·8·24 
Hard DriveHard DriveHard DriveOptical Drive
OCZ Vertex 4 128GB OCZ Vertex 2 120GB WD Caviar Black 1TB LG DVD-RW 
CoolingCoolingOSOS
Noctua NH-D14 Accelero S1 R.2 + 2x NF-F12 Se7en x64 Se7en x32 
PowerCase
Antec TP-650W CM HAF 912 + 
  hide details  
Reply
post #3 of 3
Thread Starter 
hmm, well that's just what i found, i couldn't tell you the volts, i dont have anything to measure it with smile.gif

i went into the bios and put it down to the min of 200rpm, because it kept giving me a fan error. and that fixed it.

but yea, thanks for those vids, it was very interesting.
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