Did you also put thermal paste between the slug and the case?
Did you also put thermal paste between the slug and the case?
I found an old 3u server chassis and put a regular atx motherboard power supply in it. 4 noctua 80mm fans and it’s relatively quiet for a server.
Bend the end of a zip tie into a U shape roughly the size of hole spacing and try feed it in one hole and out another.