SELLING SHAREHOLDER AGREEMENT

   This Selling Shareholder Agreement (this "Agreement") dated as of ________, 
is between STB SYSTEMS, INC., a Texas corporation (the "Company"), and each of 
William E. Ogle, William D. Balthaser, Jr. and Mark S. Sims (collectively, the 
"Selling Shareholders").

   WHEREAS, the Company expects to undertake a public offering (the 
"Offering") of certain shares of its Common Stock, of which approximately 
2,775,000 shares will comprise the portion to be offered by the Company and 
approximately 225,000 shares will comprise the portion to be offered by the 
Selling Shareholders (it being understood that the Company and the Selling 
Shareholders will each further grant an option to sell approximately 225,000 
and 225,000 additional shares, respectively, to cover the underwriters' 
overallotment option);

   WHEREAS, pursuant to the proposed terms of the Underwriting Agreement (the 
"Underwriting Agreement") by and among the Company, the underwriters 
participating in the Offering (the "Underwriters") and the Selling 
Shareholders, the Underwriters are requiring that the Selling Shareholders 
indemnify them against certain losses, claims, damages or liabilities arising 
out of or based upon the contents of the Registration Statement relating to 
the Offering or certain representations of the Selling Shareholders included 
in the Underwriting Agreement;

    WHEREAS, the Selling Shareholders have indicated to the Company that a 
precondition to their participation in the Offering is the Company's 
indemnification of the Selling Shareholders for any losses, claims, damages 
or liabilities arising out of the Offering, including the indemnification 
and contribution obligations owed to the Underwriters under the Underwriting 
Agreement;

   WHEREAS, the Board of Directors has given extensive consideration to the 
contents of this Agreement and has determined that it is in the best 
interests of the Company and its shareholders as a whole that the Company 
indemnify the Selling Shareholders as requested, because the Board of 
Directors believes that (i) the sale of shares by each of the Selling 
Shareholders through a registered public offering will provide for a more 
orderly sale of such stock to the public than would occur if such 
shareholders were to sell such shares under Rule 144 (including consideration 
that the market price for the Company's Common Stock is more likely to be 
adversely affected by sales of stock under Rule 144 than through a registered 
public offering), (ii) the sale of the shares by the Selling Shareholders 
would increase the amount of Common Stock publicly held by persons not 
affiliated with the Company, (iii) the Underwriters will be able to place the 
shares to be sold by the Selling Shareholders with purchasers, such as 
institutional investors, that the Company desires, (iv) the Selling 
Shareholders would agree to execute a "lock-up agreement" with the 
Underwriters, which would enhance the Company's ability to complete 
negotiations with the Underwriters, as well as the Offering itself, and 
facilitate a calm aftermarket in the Company's stock and (v) the inclusion of 
the Selling Shareholders' shares in the Offering will improve the terms upon 
which all shares will be sold in the Offering.

   NOW, THEREFORE, in consideration of the foregoing and the mutual covenants 
set forth in this Agreement, the parties agree as follows:



     1.  INDEMNITY. The Company agrees to indemnify each Selling Shareholder 
for all losses, claims, damages or liabilities arising out of the offer and 
sale of shares in the Offering (in such Selling Shareholder's capacity as 
such), including any losses, claims, damages or liabilities arising out of the 
Selling Shareholders' indemnification and contribution obligations owed to the 
Underwriters under the Underwriting Agreement.  In the event that a claim for 
indemnification arises hereunder otherwise than as a result of a claim made 
against a Selling Shareholder under the terms of the Underwriting Agreement, 
such Selling Shareholder shall immediately notify the Company and the Company 
shall at its expense be entitled to assume the defense of any action, suit or 
proceeding against, or investigation or inquiry of, such Selling Shareholder; 
provided, that in the event the Company assumes such defense, any legal or 
other expenses subsequently incurred by such Selling Shareholder in connection 
with the defense of the action, suit or proceeding shall be borne by such 
Selling Shareholder and the Company shall not be responsible therefor.  In the 
event that a claim for indemnification arises hereunder as a result of a claim 
made against a Selling Shareholder under the Underwriting Agreement, the 
Company shall pay to the Selling Shareholder any amount for indemnification or 
contribution in accordance with the terms of the Underwriting Agreement at 
the same time as such Selling Shareholder is obligated to pay any such amount 
to any Underwriter.  The right to indemnification as provided by this 
Agreement shall be enforceable by any Selling Shareholder in any court of 
competent jurisdiction.

     2.  SUBROGATION. If the Company makes any payment under this Agreement, 
the Company shall be subrogated to the extent of such payment to all of the 
rights of recovery of the Selling Shareholders to whom payment is made, who 
shall execute all papers required and shall do everything that may be 
necessary to secure such rights.

     3.  SEVERABILITY. Each of the provisions of this Agreement is a separate 
and distinct agreement and independent of the others, so that if any such 
provision shall be held to be invalid or unenforceable for any reason such 
invalidity or unenforceability shall not affect the validity or 
enforceability of the other provisions hereof.

     4.  NOTICE. Any notice, consent or other communication to be given under 
this Agreement by any party to any other party shall be in writing and shall 
be (a) personally delivered, (b) mailed by registered or certified mail, 
postage prepaid with return receipt requested, (c) delivered by overnight 
express delivery service or same-day local courier service or (d) delivered 
by telex or facsimile transmission to the address set forth beneath the 
signature of the parties below or at such other address as may be designated 
by the parties from time to time in accordance with this Section. Notices 
delivered personally, by overnight express delivery service or by local 
courier service shall be deemed given as of actual receipt. Mailed notices 
shall be deemed given three business days after mailing. Notices delivered by 
telex or facsimile transmission shall be deemed given upon receipt by the 
sender of the answerback (in the case of a telex) or transmission 
confirmation (in the case of a facsimile transmission).

     5.  GOVERNING LAW. This Agreement shall be interpreted and enforced in 
accordance with the laws of the State of Texas.

     6.  BINDING EFFECT; SUCCESSORS. This Agreement shall be binding upon 
each Selling Shareholder and upon the Company, its successors and assigns and 
shall inure to the benefit of each Selling Shareholder, its heirs, executors, 
administrators, personal representatives and assigns and to the benefit of 
the Company, its successors and assigns.

     7.  AMENDMENT. No amendment, modification, termination or cancellation 
of this Agreement shall be effective unless in writing signed by both parties 
hereto.


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     IN WITNESS WHEREOF, the parties hereto have executed this Agreement on 
the date first above written.

                                       STB SYSTEMS, INC.


                                       By:
                                           --------------------------------
                                           Randall D. Eisenbach, Executive 
                                           Vice President and Chief Operating
                                           Officer

                                           1651 North Glenville Drive
                                           Richardson, Texas 75081
                                           Facsimile: (972) 437-9631


                                       ------------------------------------
                                       William E. Ogle
                                       c/o STB Systems, Inc.
                                       1651 North Glenville Drive
                                       Richardson, Texas 75081
                                       Facsimile: (972) 437-9631


                                       ------------------------------------
                                       William D. Balthaser, Jr.
                                       c/o STB Systems, Inc.
                                       1651 North Glenville Drive
                                       Richardson, Texas 75081
                                       Facsimile: (972) 437-9631


                                       ------------------------------------
                                       Mark S. Sims
                                       c/o STB Systems, Inc.
                                       1651 North Glenville Drive
                                       Richardson, Texas 75081
                                       Facsimile: (972) 437-9631


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