Shaktiganesh, a student of a private school in Karamadai, hanged himself in his house in Periyanaicken Palayam on the city outskirts when his parents had gone out, police said.
He had expressed the fear that he may score lower marks or fail in the examinations, which led to the suicide even before the results were announced, they said.
However, the boy, son of a retired postal employee, scored 861 marks out of 1200 marks and cleared the exam, police added.