cannot renew ip address

i replaced a computer for one of the users, connecting it to the same port. the problem is it cannot renew the ipaddress, it is still tied to an old ip.

if you ping the computer name : request timed out and display the old ip address.
if you run ipconfig it will give a different ip address.
pc is able to connect to the network its just that we cannot do remote connection using the computer name but can remote using the ip address.

we tried to
release renew ipaddress, flush dns
delete arpcache
remove/add pc from domain

but it still has the ipaddress of the old pc.
pc is fresh from clean install.

any other suggestions?