There are two different types of ILM (Independent Loading Mechanism) for Intel’s LGA2011 based Xeon CPUs: Square ILM with 80x80mm hole spacing and Narrow ILM with 56x94mm hole spacing. The mounting system of the NH-U12DX i4/NH-D9DX i4 3U/NH-U9DX i4 is fully compatible with both types: