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Fan controller displaying incorrect RPM

post #1 of 4
Thread Starter 
Hi, I've recently messed around with my fan cabling and changed my splitter cable for my 3x Cougar rad fans. Before they were connected to my Lamptron fan controller with a 9x Phobya splitter cable (where only one 3 pin cable was wired to transmit fan RPM info), but now they're just connected with a 3x Bitfenix splitter. However, now my fan controller displays the RPM as being (I assume) far less than what I believe it actually is. For example, whereas before with the channel dial at 2 o'clock it reported 900 rpm, but with the Bitfenix cable it displays 600 rpm. As far as I can tell temp wise though, the fans are still pushing the same amount of air as previously. Can anyone think of a reason for this? thinking.gif
post #2 of 4
Have you tried connecting each fan individually and seeing if they are all showing the correct reading (or if perhaps one is reporting 600 rpm as it will only go as high as the lowest one) ?

Id say do that first and if they all show the correct readings, proceed from there
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The Laptop
(6 items)
 
  
CPUGraphicsRAMHard Drive
Intel i7 2860QM AMD Radeon HD 6770M Corsair Vengence 1600MHz Samsung 840 Pro 256GB 
OSMonitor
Mac OS X 10.8 1680 x 1050 anti-glare high resolution  
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post #3 of 4
Splitters will totally mess with fan speed detection, because you're shorting the output of the speed sense pin on each fan together. If that Bitfenix splitter has the sense wire bound together for each fan -- there's your problem.

Greg
post #4 of 4
Thread Starter 
Quote:
Originally Posted by appleg33k85 View Post

Have you tried connecting each fan individually and seeing if they are all showing the correct reading (or if perhaps one is reporting 600 rpm as it will only go as high as the lowest one) ?

Id say do that first and if they all show the correct readings, proceed from there
Ok, thanks, I'll try this.
Quote:
Originally Posted by hammong View Post

Splitters will totally mess with fan speed detection, because you're shorting the output of the speed sense pin on each fan together. If that Bitfenix splitter has the sense wire bound together for each fan -- there's your problem.

Greg
Yeah, this is what I suspected was the problem. The Phobya cable had one extension that was very specifically labelled 'RPM sensor', so I'm guessing that this was the only extension of the splitter that had an active sense wire, so in effect the fan controller was only reading the speed of 1 fan. The Bitfenix splitter had no such labels, so I do believe what you described is the issue. Thanks, +1 rep
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