I've always liked Noctua's mounting systems, as they're easy for a single person to do. The NH-L12 follows suit continuing the lineage of Noctua's "Secure-Firm 2" mounting system. The inclusion of a screw driver which has plenty of reach through the holes in the heatsink, attaching the cooler to the board is very simple and easy. The most difficult part by far is wiggling the bottom fan betweein the heatsink and motherboard, as the mounting brackets and edge of the fan tend to want to get caught on everything in their way. However, you can probably get away with installing the bottom fan first, and the screwdriver will fit between fan blades, something that clearly occured to us after-the-fact.
The cooler enables plenty of clearance for high-profile RAM kits, like our Patrio Viper Xtremes, and the cooler can be rotated whichever way fits the best, since the airflow goes the same direction either way. The 120mm fan will mount easily on the bottom side of the heatsink for a pull configuration, just as the 92mm fan will. The 120mm fan will probably cause clearance issues if the cooler is mounted with the side opposite the heatpipes hovering over the RAM slots, but the 92mm fan solves that problem (and will perform about the same, as we'll explain in the "Performance" section). The heatpipes do not extend as far away from the cooler as we've seen on other downflow coolers, but still extends far enough to block the innermost RAM slots on our ASUS P67 Sabertooth motherboard. This could be remedied by turning the cooler 90 degrees, and wouldn't change the performance by any noticeable margin.