To install the cooler, you will need to remove the mainboard 100% from your system. The Hyper N520 has the mounting screws faced down and the heatsink has to be tightened down from the backside of the motherboard with nuts. Having a third hand would be a requirement.
So you put the cooler upside down, then position the motherboard over the 4 screws and washers, and then at the backside you secure them screws with four washers and nuts. For LGA 775 processor you can use a back plate here, but using that I felt we'd have even less clearance in-between the motherboard tray and motherboard.
We'd very much like to to see Cooler Master move away from this mounting system, there are so much more better solutions out there.
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