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                                                                 Exhibit 10.1

             AMENDMENT TO EMPLOYMENT AGREEMENT FOR EXECUTIVE OFFICER

     THIS AMENDMENT TO EMPLOYMENT AGREEMENT FOR EXECUTIVE OFFICER 
("Agreement") made the 13 day of December, 1998, between STB SYSTEMS, INC., 
a Texas corporation (the "Company"), and WILLIAM E. OGLE ("Executive").

     WHEREAS, Executive and the Company have executed an Employment Agreement 
dated as of November 1, 1996 (the "Employment Agreement"); and

     WHEREAS, under an Agreement and Plan of Reorganization dated as of 
December 13, 1998 (the "Merger Agreement"), the Company will become a 
wholly-owned subsidiary of 3Dfx Interactive, Inc., a California corporation 
("3Dfx"); as of the Effective Time (as defined in the Merger Agreement) (the 
"Merger"); and

     WHEREAS, at the Effective Time of the Merger, 3Dfx will assume the 
Employment Agreement and become the employer thereunder; and

     WHEREAS, Executive and the Company desire to set forth in this Agreement 
the amended terms for Executive's continued employment following the Merger.

     NOW, THEREFORE, in consideration of the mutual covenants and agreements 
herein contained, the parties agree as follows:

                                    FIRST

     The terms of this Agreement shall become effective only at the 
Effective Time of the Merger, at which time 3Dfx shall assume the Employment 
Agreement, as amended by this Agreement, and all references in such 
Employment Agreement and this Agreement to the "Company" shall be deemed to 
refer to 3Dfx. Paragraphs 1 and 2 of the Employment Agreement will be amended 
in their entirety to provide as follows:

"1.  EMPLOYMENT.  The Company hereby agrees to employ Executive and Executive 
hereby agrees to serve the Company, on the terms and conditions set forth 
herein, for the period commencing on the Effective Time of the Merger and 
expiring on the date that is the one year anniversary of such date (unless 
sooner terminated as hereinafter set forth); provided,  however, that 
commencing on such anniversary date, and each annual anniversary of such date 
thereafter, the term of this Agreement shall automatically be extended for 
one additional year unless, at least 30 days prior to any such anniversary 
date, the Company or the Executive shall have given notice that it does not 
wish to extend this Agreement. The term of this Agreement, as it may from 
time to time be extended this Agreement. The term of this Agreement, as it 
may from time to time be extended in accordance with this Paragraph, may be 
referred to herein as the "Period of Employment."

     2.  POSITION AND DUTIES. Executive shall serve as an Executive Vice 
President of the Company, performing the functions and duties as shall be 
prescribed from time to time provided that such functions and duties are 
consistent with and attendant to Executive's position or other positions that 
he may hold from time to time. Executive shall devote his full working time 
and efforts to the business and affairs of the Company and the promotion of 
its interest and


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perform all duties and services on behalf of the Company necessary to carry 
out such functions."

                                    SECOND

     Subparagraphs 3a. and 3b. of the Employment Agreement will be amended 
in their entirety to read as follows:

     "3.  COMPENSATION AND RELATED MATTERS.

          a.  BASE SALARY. Executive shall receive an annual base salary 
("Base Salary") at the rate of Two Hundred Seventy-five Thousand Dollars and 
No/100 Cents ($275,000.00) during the period ending on the first anniversary 
of the Effective Time of the Merger. Thereafter, Executive's Base Salary 
shall be redetermined at least 30 days before each annual anniversary in an 
amount to be fixed by the Board of Directors of the Company or the 
Compensation Committee thereof. The term "Base Salary" as used in this 
Agreement shall mean, at any point in time, Executive's annual base salary at 
such time. The Base Salary shall be payable in substantially equal 
semi-monthly installments or in accordance with the Company's regular payroll 
practices.

          b.  INCENTIVE COMPENSATION. In addition to Base Salary, Executive 
shall participate in the Company's incentive compensation plan for its senior 
executive management employees."

                                    THIRD

     Paragraph 4 of the Employment Agreement will be amended in its entirety 
to read as follows:

     "4.  OFFICES. Executive agrees to serve as a director of the Company, if 
elected or appointed thereto, provided he is indemnified for serving in such 
capacity on a basis no less favorable than is currently provided by the 
Company's By-laws. If elected as a director of the Company as of the 
Effective Time, Executive will serve as the Vice Chairman of the Company's 
Board of Directors.''

                                    FOURTH

     Subparagraph 9c of the Employment Agreement will be amended to delete 
therefrom Subsection (A) in its entirety. Subsection (C) of the definition of 
"Good Reason" in Subparagraph 9d of the Employment Agreement will be amended 
in its entirety to reflect more clearly the original intent of the parties, 
to read as follows:

     "(C) without Executive's consent, a reduction of Executive's Base Salary 
to an amount less than previously determined and fixed for the immediately 
preceding twelve-month period by the Compensation Committee in accordance 
with Subparagraph 3(a) other than a reduction deemed necessary by the Board 
for all executive officers;"



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     Paragraph 12 of the Employment Agreement will be amended in its entirety 
to provide as follows:

     "12.  NOTICE. For purposes of this Agreement, notices and all other 
communications provided for in the Agreement shall be in writing and shall be 
deemed to have been duly given when delivered or mailed by United States 
certified mail, return receipt requested, postage prepaid, addressed as 
follows:

               if to the Executive:

                    At his home address as shown
                    in the Company's personnel records;

               if to the Company:

                    3Dfx, Inc.
                    4435 Fortran Drive
                    San Jose, CA 95134
                    Attn: Secretary

or to such other address as either party may have furnished to the other in 
writing in accordance herewith, except that notices of change of address 
shall be effective only upon receipt."

     IN WITNESS WHEREOF, the parties have executed this Agreement on the date 
set forth above.


                                      STB SYSTEMS, INC.


/s/ William E. Ogle                   /s/ Randy Eisenbach
-----------------------------         ------------------------------
WILLIAM E. OGLE                       By: RANDY EISENBACH
                                      It.: COO
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