The NH-L12 is not much different than Noctua's other high-performance downflow coolers other than the dimensions are all basically scaled down. The depth of the heatsink itself is smaller, the overall height made a bit more squat, and the tops-down area perfectly accommodates a 120mm fan, as opposed to 140mm fans on its larger brethren. The fins are sturdy and the fans clip easily and firmly into grooves on the side of the fins. The clearance from the base to the fins are just enough to squeeze the fans underneath. We were able to install both the 92mm fan and the 120mm fan on the bottom of the heatsink, as shown above.
Removing the fans really accentuates how narrow the heatsink fins are. The four heatpipes rise and curve nearly-vertically, so they'll pose less of a clearance problem than the larger downflow coolers we've tested. Both fans use Noctua's fluid dynamic bearings and whisper quiet fan blade designs. The 92mm fan utilizes vortex control notches to minimize noise-inducing vortices, which is more noticeable on smaller fans which turn at a higher RPM. These fans really are the best in the business in terms of airflow to noise ratios. The cooler has an overall thermal dissipation power (TDP) of only 95W, which means you won't be pushing any of your processors too hard, but something tells me that if you're looking for a low-profile cooler, this probably is of utmost concern. However, the release of the BitFenix Prodigy has enabled high performance systems in a very small package, and if you're still looking for something with some good thermal performance, you'll still have some headroom with the NH-L12.
The contact base is machined and polished and is mirrow smooth and exceptionally flat. The four heatpipes are laid straight through the center of the base, and you can see the space left for two more heatpipes, as we see on the larger downflow coolers. The 120mm cooler has vibration-reducing rubber pads on the corners which also helps provide a bit of "grip" to hold it firmly in place on the heatsink. The fans snuggle tightly in between the base and the heatsink, and the lowermost fan provides a burst of airflow right down on the base itself. Downflow coolers also have the added benefit of cooling the Northbridge and RAM, which can boost overall system stability, although with this cooler you shouldn't be pushing your CPU to where instability will be a concern.