"The Noctua NH-L12 is a lower profile heatsink that stands 93mm tall and is a little over 130mm square. The heatsink comes with two fans; a 120mm NF-F12 PWM fan on top and a 92mm NF-B9 PWM fan tucked away beneath the fins. In a nod to being flexible, the top fan can be knocked off the NH-L12 to lower its height to 66mm for really compact computer cases if necessary. That's a far cry more compact than the typical 160mm tall tower heatsink!"
Any major computer upgrade generally requires a full software reinstall too. No so if you heed the advice in the guide to Upgrading a Motherboard without Reinstalling. PCSTATS Tips