Dont know name but look like oem mobo part somekind.

I have a similar part on a Slot A motherboard that I bought NOS/full package. Says it's a heatsink retainer or something like that...

There was 2 piece bracket that would sandwich the bottom most tall fins on OEM systems that used large alum heatsinks without fans, there were also angle attached brackets on some smaller heatsinks with fans that could be pinned right to the board as well.

I have a few of them but here is a quick page I found from a manual.

Pic here https://commons.wikimedia.org/wiki/File:Penti … ull_shot%29.jpg

Grem Five wrote on Today, 00:18:

There was 2 piece bracket that would sandwich the bottom most tall fins on OEM systems that used large alum heatsinks without fa […]
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There was 2 piece bracket that would sandwich the bottom most tall fins on OEM systems that used large alum heatsinks without fans, there were also angle attached brackets on some smaller heatsinks with fans that could be pinned right to the board as well.

I have a few of them but here is a quick page I found from a manual.

Beat me to it. Indeed, MANY OEM systems used this bracket for oversized coolers, typically only SECC1 Slot1 computers. I've seen it used on the laying-down Slot1 boards, too. It's pretty much only necessary if you HAVE one of those over-sized coolers, as they have a slot at the bottom for the retaining bar to go into.

Example from a Dell D333:

If your heart is set on having one, it's on my list of things to design/3d print, so I'll have it to share, eventually. Otherwise, I say, "remove the bracket, it's ugly". I do have a few of these loose for that reason.

Thanks everyone! I feel much more confident now.