Use the old fish tank method. From what I saw, you won't need a heat sink.
The different ways to attach the Heavy Heatsink, mentioned in this forum above, seem difficult and are mostly specialized for that motherboard situation only. (Except for plastic straps and epoxy. But often epoxy will not reliably stick to some surfaces.)
In my case, three of the four hook holes were broken, in the plastic "hold-down" frame and the plastic not workable for an epoxy fix. I would modify the plastic frame, such as drill holes in it, but the plastic frame is impossible to remove, and removing the motherboard, for access to the plastic frame, seemed too difficult compared to the following:
I was able to make a somewhat complex wire rectangle, that ran under the respective four corners of the plastic frame, with bent up sections on each side of the heatsink: The bent up portions, provided solid places for the 4 hold down hooks that hold the heatsink.
Send me an email, and I can send photos of what this wire rectangle looks like, as well as photos of what the final assembly looks like.
The fitting of the wire rectangle was accomplished with the motherboard in place. The wire if bendy enough for me to slice it around the bottom edges of the plastic rectangle, and then it snaps into place. Add HSF, and computer boots up great!!!
Google will find me at Professor Henry Gurr
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