Cave grabbed the first try in the 32nd minute, Humphreys adding the conversion, and two minutes later Ulster had their second try with an even better effort from Cave after a great break by Ian Whitten. Humphreys again added the extras.
Ian Humphreys added a couple of conversions and a penalty while replacement Paddy Jackson added a penalty of his own. Cardiff’s only replay was a late penalty by fly-half Ceri Sweeney.
A late tackle on Humphreys by Casey Laulala saw the Ulster fly-half replaced by Jackson who quickly ended the scoring with a penalty.
ULSTER: J Payne; C Gilroy: D Cave (D’Arcy, 40), N Spence, I Whitten; I Humphreys (Jackson, 74), P Marshall (Porter, 68); D Fitzpatrick (McAllister, 53), A Kyriacou (Brady, 65), J Cronin (Macklin, 80), L Stevenson, D Tuohy (McComb, 80), P Wannenburg, C Henry, R Diack (McComish, 65).
CARDIFF BLUES: C Czeka: T James; C Lualala, G Evans (Hewitt, 40), A Cuthbert; C Sweeney, L Jones (Rees, 46); T Rhys Thomas (Trevett, 67), S Andrews, M Patterson, P Tito, capt (Down, 67), M Molitika, M Williams (Young, 68), X Rush.
Referee: James Jones (WRU).