I used a Cooler Master LC120E AIO cooler on it and it made a huge difference in temps.
The socket is a LGA1155 and idetailed nformation about the board can be found here.
https://support.hp.com/us-en/product/omen-by-hp-875-0000-obelisk-desktop-pc-series/23302709/model/23574497/document/c06124984