Odd fan behaviour

[matt.xx]

Hi All,

I've recently replaced three stock chassis fans in my system.

I use Fan Xpert 2, as part of AI Suite II, and have ran the auto fan optimisation. The strange thing is that after the fan optimisation has finished the two top fans stop spinning, but the rear continues to spin.

The only way I've found to start the fans again is to use the click 'Turbo' mode in the Fan Xpert 2 interface. This then allows all of the fans to spin, but the rear fan is around 20rpm faster than the top fans. Could the rpm be higher for the rear fan due to the fact that the top fans go through the 30cm extension cable?

Does anybody know why all three fans wont spin in 'Standard' mode (Fan Xpert 2 interface)?

MB: Asus P8Z77-V Pro
Fans: 3 x Noctua NF-F12 PWM 120mm Focused Flow PWM Cooling Fan
Fan positioning: Two at the top, one at the rear.
Connections: Rear is connected directly to the MB and the two top fans each go through 4 pin 30cm extension cables which were provided with the fans and connect to the MB.

Fan profiles have been set to 'Silent' in the BIOS.

Thanks in advance, guys!

Matt

 

[MillsyOC]

IIRC you want to set the fans to full-speed/default-speed in the BIOS and use just the FanXpert software to control them. You can control the full range of RPM using FanXpert.