Glasgow Warriors are the only club to have won each of their opening three fixtures after overcoming the Cheetahs.
Pro14 champions Leinster were defeated by last season's runners-up Scarlets in a tense clash on Saturday.
John Cooney's kicking got Ulster up and running, while Connacht's Craig Ronaldson fell just short and Munster ran riot in Pro14.
Leinster were unable to seal a home semi-final as Benetton Treviso consigned them to a shock home defeat in the Pro14.
There were wins for Glasgow Warriors, Edinburgh and Cheetahs in Pro14 on Saturday, with Duncan Weir among the star performers.
The Southern Kings scored six tries against Dragons to claim their first Pro14 victory at the 17th time of asking.
Rob Harley's record 178th appearance for Glasgow Warriors was one to forget as they were beaten by Munster.