Asus PVI-486SP3 PS/2 mouse pinout
The Asus board has a relatively uncommon PS/2 mouse header on the board - at a time when serial mice where still in the majority.
Unfortunately there isn't a standard connector to go from this header to a female PS/2 connector.
Asus Motherboard Header
Female PS/2 Connector
Here's what a standard female PS/2 connector looks like, and the pin assignment, looking in to the connector from the side you plug in the mouse connector, not the solder side: