Noctua, like always, continues to make its products with considerable thought and care. The NH-D9L fills a even greater gap than the NH-U9S, while still covering the basics by focus on the low performance stock coolers from both Intel and AMD and provides something that can dissipate a large volume of heat within small confinement. The extra bit difference here is the D9L is 3U compatible allowing for a even smaller footprint reaching only 110mm. This is where I often run into this problem with a chassis, where I find it to be great, but lack the height to install a decent size aftermarket cooler. A great example would be Cooler Master Stacker series with its ITX chassis. That chassis was a rough sell considering the zero extra space. This is where Noctua comes in!