There have been several occasions when I have cringed at the unecessary complexity in certain CPU cooler mounting methods. In my personal opinion, the Phanteks PH-TC12DX has the best no frills and minimal fuss mounting systems that I've seen, but the Deepcool Assassin comes very close. Aside from the well-labeled and precision-drilled backplate, the Intel mounting kit includes a set of rubber pieces that slide over the four polished bolts once they are inserted to hold them in place. They also pull double duty by protecting your motherboard from scratches. Losing mounting hardware inside a densely-packed chassis quickly becomes frustrating, so being able to concentrate on one part of the assembly process at a time is much appreciated on the part of a builder. These rubber fastener "clips" make it a cinch to hold the Intel backplate against the motherboard with one hand, leaving your second hand free to mount the remaining bushings, brackets, and collar nuts. For some odd reason, Deepcool decided to take a step backward in their CPU cooler mounting ingenuity by making the collar nuts very small, so take care not to lose them!
Despite its size, the Assassin slipped inside our mid-tower test bench without raising any alarms
Once this first half of the installation is complete, just apply some of the included thermal paste, tighten the retention bracket down over the cooler baseplate, and finally mount the two fans. It's a fairly tight squeeze for the 140mm fan between the heatsinks, and an even tighter squeeze for your hands as you attach the fan retainer clips. Best keep your cables tidy and clear out as much room around the socket as possible. If you intend to mount the 120mm to the front of the heatsink for a push/pull setup, you'll most likely need to temporarily remove any DIMMs from their slots to give you enough space. A slight annoyance for some, but I would much rather accidentally drop a large, brightly-colored stick of RAM inside my case than a tiny screw that will take many minutes and a flashlight to find. Both fan cables are extra long, so you shouldn't have any issue reaching the nearest motherboard header pins. I won't say that installing the Deepcool Assassin was a walk in the park, but compared to some smaller coolers with miniscule screws and complicated retention brackets, the thoughtful design of the mounting hardware makes a world of difference. But as with any large CPU cooler, if you have the chance to mount it while your motherboard is outside of a chassis, take it!