Page 103 of 134


                                                                       EXHIBIT 5




                                                                Page 104 of 134


                CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,
                             AS ENACTED PURSUANT TO
               SECTION 906 OF THE U.S. SARBANES-OXLEY ACT OF 2002


                  ATI Technologies Inc. (the "Company") is filing its annual
report on Form 40-F for the fiscal year ended August 31, 2003 (the "Report")
with the U.S. Securities and Exchange Commission.

                  I, K.Y. Ho, Chairman and Chief Executive Officer of the
Company, certify, pursuant to 18 U.S.C. section 1350, as enacted pursuant to
section 906 of the U.S. Sarbanes-Oxley Act of 2002, that to the best of my
knowledge:

                  (i)  the Report fully complies with the requirements of
                       section 13(a) or 15(d) of the U.S. Securities Exchange
                       Act of 1934; and

                  (ii) the information contained in the Report fairly presents,
                       in all material respects, the financial condition and
                       results of operations of the Company.





//K.Y. Ho//
------------------------------------
K.Y. Ho
Chairman and Chief Executive Officer
January 16, 2004







                                                                Page 105 of 134


                CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350,
                             AS ENACTED PURSUANT TO
               SECTION 906 OF THE U.S. SARBANES-OXLEY ACT OF 2002


                  ATI Technologies Inc. (the "Company") is filing its annual
report on Form 40-F for the fiscal year ended August 31, 2003 (the "Report")
with the U.S. Securities and Exchange Commission.

                  I, Terry Nickerson, Senior Vice President, Finance and Chief
Financial Officer of the Company, certify, pursuant to 18 U.S.C. section 1350,
as enacted pursuant to section 906 of the U.S. Sarbanes-Oxley Act of 2002, that
to the best of my knowledge:

                  (i)  the Report fully complies with the requirements of
                       section 13(a) or 15(d) of the U.S. Securities Exchange
                       Act of 1934; and

                  (ii) the information contained in the Report fairly presents,
                       in all material respects, the financial condition and
                       results of operations of the Company.





//Terry Nickerson//
----------------------------------
Terry Nickerson
Senior Vice President, Finance and
Chief Financial Officer
January 16, 2004