I have a new build using a Corsair H115i RGB Platinum cooler. Everything seems to be working as expected through software, reported RPM. fan speed control, LED control etc. The thing that is odd is the fan speed reported to the BIOS.
The MB is a new Asus Crosshair 8 wifil. The Corsair block has a ribbon cable coming off it with all but 1 conductor going to the SATA power and the last conductor goes to a 3 pin connector that plugs into the motherboard fan connector.
The software reports the fan speeds to be around 450 RPM and the pump is running about 2000 RPM all is well.
The BIOS on the motherboard is reporting about 4500 RPM.
My questions are:
1) what should be reported to the MB, fan 1, fan 2 or the pump RPM or something else?
2) shouldn't there be a ground wire going to the fan connector that goes to the motherboard?
Does this FAQ answer my first question?
A11. I have my cooler plugged into the CPU_FAN header and I’m seeing some really crazy fan speed readings for CPU_FAN. What’s up with that?
Most Corsair coolers report RPMs to the CPU_FAN header equal to approximately ½ of the fan speed. This prevents a CPU Fan warning from your BIOS when booting but and can give you an approximate speed of your pump if you aren’t running Link but otherwise it’s nothing to be concerned about. Note that the new Pro series coolers (H150i Pro and H115i Pro) report actual pump speed on the CPU_FAN header.