Apr 1, 2009

I recently built a new computer and am getting a CPU Fan Error when I turn it on. I am using the Noctua NH-U12P on an Asus P6T Deluxe V2 board. The stock fan that came with my i7 had four prongs, but the two fans that came with the new HSF have three prongs each, so I can't plug them into the CPU_Fan slot. Can I just disable the CPU_Fan in the BIOS, or is it important to have one of the fans blowing into the heatsink plugged into that slot?

Thanks in advance for any and all help!


First off, since you have two fans in the Noctua system, I assume you do not have the NH-U12P plain cooler. You must have the NH-U12P SE1366.

I also assume you did not intend to run with no CPU cooling. You simply meant to hook it up independent of the mobo connector and then tell the BIOS not to monitor or control the CPU cooler. But it turns out none of this is necessary.

Your solution is in Noctua's FAQ page for this unit. Go to

and look near the bottom for the item about 4-pin PWM connectors. Its says:

Can I run Noctua fans on 4-pin PWM connectors and use my mainboard’s automatic fan controller?
Yes. You can simply connect our fan's 3-pin connector to the 4-pin PWM sockets of today's mainboards so that the fourth pin that transmits the PWM signal is left blank (due to the shape of the connector, there's no danger of reversing polarity). Most current mainboards are capable of controlling fans not only via PWM, but also by adjusting the supplied voltage. In some cases, this may require you to change BIOS options like "Fan Control Mode" from "PWM" to "Voltage" or "Analog". Please consult your mainboar's manual in this regard. However, most current mainboards use an "auto" setting by default that automatically chooses PWM or voltage based regulation according to the connected fan.

Then it shows you nice clear pictures of the connector and how it fits.