O'Brien took So You Think to the front at the entrance to the long run in and extended him only for about a furlong as he sealed yet another group one, albeit one of the weakest he has ever contested.
The Dermot Weld-trained Famous Name, the 7-1 second favourite battled on bravely for second, but at no stage did he ever look like troubling So You Think, who was simply in a different class.
O'Brien slipped So You Think, the $1.20 favourite, back into cruise control over the final 150m as he coasted to a six-length win.
So You Think, nearing the end of his racetrack career, will next head to Royal Ascot where he is expected to start in the Prince Of Wales Stakes (2000m). It was the race that he ran second in last year behind Godolphin's Rewilding.
So You Think's career is likely to end in the Coral Eclipse Stakes, a race he won last year.
With his latest success in a race that carried a first prize purse of $167,017, So You Think has now earned A$7,656,795.
While he has not been the world champion his new owners were hoping for when they purchased him out of the Bart Cummings stable 18 months ago, So You Think is certain to be popular in his first breeding season with Australian breeders.
Meanwhile, a horse who went so close to winning this season's Cox Plate has found his home at stud.
Telecom Derby winner and reigning Horse of the Year Jimmy Choux will stand at Rich Hill Stud in Waikato.
That comes after an agreement reached by the farm and Nearco Stud principal Greg Tomlinson with the former outstanding galloper's owner-breeders Richard and Liz Wood.
"We weren't originally planning to have a new stallion, but the decision by Sir Percy's English owners to rest him from shuttle duty this year coincided with the retirement of Jimmy Choux," Rich Hill studmaster John Thompson said.
"We feel he will be a great addition to the roster here and a horse of his charisma will command a real following and enjoy strong support from the New Zealand breeding industry. He also made such a mark in Australia that his future progeny will demand serious attention from overseas buyers."
Thompson said discussions at the recent May sale at Karaka with Tomlinson and his bloodstock manager Adrian Clark had provided the catalyst to Rich Hill becoming Jimmy Choux's new home.
Rich Hill and Nearco Studs have taken significant holdings in the stallion and the Woods have retained an interest.
Trained throughout his career at Hastings by John Bary, Jimmy Choux was the winner of the Wakefield Challenge Stakes at two and placed in both the Diamond Stakes and the Gr.1 Manawatu Sires' Produce Stakes.
His career went to another level at three when he completed the New Zealand 2000 Guineas-New Zealand Derby double and carried on his stellar form in Sydney in the autumn with victory in the Rosehill Guineas.
Jimmy Choux returned this season to claim the Windsor Park Plate and Spring Classic after finishing runner-up in the opening leg of the Hastings Triple Crown. He crossed the Tasman again and beat all but Pinker Pinker in the Cox Plate.
STARS SHINE
* So You Think wins another group one race in Ireland.
* The New Zealand-bred star won the Tattersalls Cup for the second time.
* He will soon be retired to stud.
* NZ Horse of the Year, Jimmy Choux, has found a home at Rich Hill Stud.
