The Bridgend forwards worked hard at the breakdown all afternoon and won penalty after penalty in the scrums. Murphy was all too happy to convert penalties in to points, kicking six of his nine attempts from the tee and adding a conversion to bring his personal haul to 20 points.
The result means Cardiff are yet to win a point in Pool 1 of the British & Irish Cup whilst the Ravens move up to third, a point behind leaders Ulster A and level with Bristol, who host the Irish Ravens at the Memorial Stadium on Sunday.
Murphy opened his account within the first minute of the match and added a second penalty minutes later, the Ravens finding themselves 6-0 up after just four minutes. Opposite number Joe Griffin had a chance to half the deficit soon after but sent his effort wide of the posts.
It was the visitors who struck next though. Blues fullback Dan Fish saw the opportunity to take a quick tap penalty on the edge of the Ravens 22 and caught the defence unawares, finding centre Owen Williams who crossed between the sticks.
Murphy recaptured the lead with two more penalties before tempers began to flair in the front-row. After a number of disruptions, referee Simon Evans lost his patience and sent Ravens hooker Ashleigh James and Cardiff prop Simon Gardiner to the sin-bin.
Cardiff then controlled possession and territory for the next ten minutes but came away with nothing, unable to break through the well-organised Ravens defensive line and it was Bridgend who closed out the half with another fantastic long-range effort from Murphy.
The visitors switched up the front-row early in the second-half to try to compete more in the scrums but the Ravens remained on top and credit for the performance must go to forwards coach and ex-Cardiff player Paul Young's hard work with the pack in training.
However, it was the backs that got Bridgend's try in the end. First, Glen Lewis nearly gathered a kick to the corner from Nathan Edwards, knocking on at the crucial moment. But the Ravens soon won possession back and Murphy threw a short ball to the onrushing Grabham who forced his way through the tackles to place the ball on the whitewash.
Cardiff replaced their half backs soon afterwards but this made little impact as the Ravens saw out the match, Murphy adding a final three to round off a fantastic performance from the home side, one which the Riverside Hardware Brewery Field crowd has been waiting to see.