AC Adapter Charger for HP 251-A111 251-A120 251-A121 251-A123W 251-A126 Desktop PC Power Supply Cord Mains PSU

It doesn't have 4 pins. It's a barrel connector. The 4 holes you see are just how the connector is molded. https://a.co/d/0eiD89x8 This one should work.