Please refer to following drawing for how to identify the different backplate revisions:

Some mainboards pose compatibility problems with the first version of the NM-IBP2 backplate included with the cooler. Please verify to use a revision 1.5 or revision 2 backplate when installing the cooler on these mainboards. All coolers manufactured since April 2013 already include the new revision backplates. Owners of coolers with rev. 1 backplates can request a new backplate from Noctua’s customer service free of charge.

The mounting is identical on all LGA115x sockets (LGA1150, LGA1151, LGA1155, LGA1156). The following coolers are thus compatible with LGA115x out of the box and don’t require any upgrades in order to be used on this platform: NH-C12P SE14, NH-C14, NH-C14S, NH-D15, NH-D15S, NH-D14, NH-L12, NH-L12S, NH-L9i, NH-L9x65, NH-U14S, NH-U12S, NH-U12P SE2, NH-U9S, NH-UD9L, NH-U9B SE2. In addition, all older models which have been upgraded with the NM-I3 kit can also be used on LGA115x without any further upgrades.

The following coolers can be made compatible to LGA115x using the NM-i115x Upgrade-Kit: NH-C12P, NH-D15 SE-AM4, NH-L9x65 SE-AM4, NH-U12, NH-U12F, NH-U12P, NH-U12P SE1366, NH-U12S SE-AM4, NH-U9, NH-U9F, NH-U9B.

The following coolers are mechanically incompatible with the NM-i115x Upgrade-Kit and can not be made compatible with LGA115x: TR4-SP3 coolers, DX-3647 coolers, DO-Series AMD Opteron coolers, NH-L9a, NH-L9a-AM4.

Some mainboards feature 4-pin fan headers that actually don‘t use a PWM signal on Pin 4 to control the fan speed but rather reduce the voltage on Pin 2 (like a standard 3-pin fan header). In this case, it may occur that the mainboard reduces the voltage so much that the fan stops. Please refer to your mainboard manual to check whether or not your mainboard has 4-pin fan headers that control the fan speed by reducing voltage on Pin 2 rather than by changing the PWM duty cycle on Pin 4:

Note that mainboard manufacturers use different terms to indicate that Pin 4 is not being used for PWM control (e.g. “+5V”, “VCC” or “NC”), but if one of these terms is used, you can be sure that the fan header does not support PWM. If Pin 4 is described as “Speed Control” or “PWM” or the like, you can be sure that the fan header supports PWM.

Unfortunately, the description of Pin 2 is not always a clear indication as some manufacturers use terms such as “Fan PWR” or “Power” for both types of fan headers. However, if Pin 2 is described as “Speed Control”, you can also be sure that the fan header does not support PWM based speed control. If Pin 2 is described as “+12V”, this is a clear indication that the fan header supports PWM.

Please also note that in some cases, the descriptions of the pin layouts in the mainboard manuals may not be correct and some models actually allow you to switch the fan headers from voltage control mode to PWM control mode in the BIOS even though the pin descriptions do not indicate PWM support. We thus recommend to look for these options in the BIOS before taking other measures. In case of doubt, please contact your mainboard manufacturer.

To resolve the issue, you can:

1. Choose a higher fan speed profile in the BIOS (e.g. „normal“ instead of „silent“, etc.) or deactivate automatic fan speed control and use a Low-Noise Adaptor instead.
   
   

2. Use the mainboard‘s fan speed control software or 3rd party tools like Speedfan to regulate the fan speed. Unlike BIOS based fan speed control, the supplied software usually checks whether the fan has stopped and increases voltage accordingly or at least offer more options to set up the fan properly.
   
   

3. If your mainboard features other 4-pin fan headers that use PWM for speed control, you can run multiple fans from these headers using Y-split cables. Make sure not to exceed the specified maximum power draw of the fan headers (usually 10-12W) though.

The specified minimum speed refers to the speed at 20% PWM duty cycle. There can be several reasons why the fan doesn‘t go as low as indicated:

1. Many mainboards do not go below 40%, 50% or even 60% PWM duty cycle on case fan headers. Please refer to your mainboard manual to verify whether the fan header actually goes down to 20% duty cycle. If that's not the case, in some cases you can use the fan speed control software supplied with your mainboard to overcome these limitations and reduce the fan speed even further. However, 3rd party tools like SpeedFan offer greater flexibility and better options to work around the limitations imposed by the mainboard vendors.
   
   
2. Some mainboards feature 4-pin fan headers that actually don‘t use a PWM signal on Pin 4 to control the fan speed but rather reduce the voltage on Pin 2 (like a standard 3-pin fan header). As the fan speed at minimum voltage is usually higher than the speed at 20% PWM duty cycle, the fan can not reach as low minimum speeds under voltage control as under PWM control. Please refer to your mainboard manual to check whether or not your mainboard has 4-pin fan headers that control the fan speed by reducing voltage on Pin 2 rather than by changing the PWM duty cycle on Pin 4:
   
   
   
   Note that mainboard manufacturers use different terms to indicate that Pin 4 is not being used for PWM control (e.g. “+5V”, “VCC” or “NC”), but if one of these terms is used, you can be sure that the fan header does not support PWM. If Pin 4 is described as “Speed Control” or “PWM” or the like, you can be sure that the fan header supports PWM.
   
   Unfortunately, the description of Pin 2 is not always a clear indication as some manufacturers use terms such as “Fan PWR” or “Power” for both types of fan headers. However, if Pin 2 is described as “Speed Control”, you can also be sure that the fan header does not support PWM based speed control. If Pin 2 is described as “+12V”, this is a clear indication that the fan header supports PWM.
   
   Please also note that in some cases, the descriptions of the pin layouts in the mainboard manuals may not be correct and some models actually allow you to switch the fan headers from voltage control mode to PWM control mode in the BIOS even though the pin descriptions do not indicate PWM support. We thus recommend to look for these options in the BIOS before taking other measures. In case of doubt, please contact your mainboard manufacturer.
   
   If your mainboard features other 4-pin fan headers that use PWM for speed control, you can run multiple fans from these headers using Y-split cables. Make sure not to exceed the specified maximum power draw of the fan headers (usually 10-12W) though.