<PAGE>

                                                                   Exhibit 10.31

                                  DOVEBID, INC.
                                  -------------

                            AMENDMENT TO CONVERTIBLE
                          SUBORDINATED PROMISSORY NOTE


         This Amendment is entered into as of April 18, 2001, by and between
Richard E. Schmitt ("Payee") and DoveBid, Inc., a Delaware corporation (the
"Company"). This Amendment amends the terms and conditions of that certain
Convertible Subordinated Promissory Note issued by the Company to Payee on March
2, 2000 in the principal amount of $1,425,000 (the "Note").

         Whereas, Payee and the Company desire to amend the Note on the terms
and conditions set forth below;

         Now, therefore, in consideration of the foregoing and for other good
and valuable consideration (receipt and sufficiency of which is mutually
acknowledged), the parties agree as follows:

         1.    Extension of Term. The second sentence of the Note is hereby
amended to read as follows.

               "The Optional Convertible Debt (as defined below) will be due and
               payable in lawful money of the United States in full on March 2,
               2004, unless the Optional Convertible Debt shall have been
               previously paid by the Company or converted pursuant to Section 2
               below, in which case the portion of the Optional Convertible Debt
               that was converted shall be satisfied in full by virtue of such
               conversion and the issuance and delivery of fully paid and
               non-assessable shares of Conversion Stock to the holder of this
               Note as set forth in Section 2 below. The principal and accrued
               interest that does not constitute Optional Convertible Debt will
               be due and payable as follows: principal in the amount of
               $250,000 will be due and payable in lawful money of the United
               States in full on March 2, 2003 and principal in the amount of
               $462,500 and all accrued but unpaid interest will be due and
               payable in lawful money of the United States in full on March 2,
               2004 (the "Maturity Date") in each case unless such principal
               and/or accrued interest shall have been previously paid by the
               Company or converted pursuant to Section 2 below, in which case
               the portion of the principal that was converted and all accrued
               but unpaid interest thereon shall be satisfied in full by virtue
               of such conversion and the issuance and delivery of fully paid
               and non-assessable shares of Conversion Stock to the holder of
               this Note as set forth in Section 2 below. Notwithstanding the
               foregoing, the Optional Convertible Debt shall be immediately due
               and payable in lawful money of the United States in full upon the
               sale, conveyance, lease, transfer or other disposition of
               substantially all of the assets of the Company to an acquirer who
               is not a reporting company

<PAGE>

               under Section 13 or 15 of the Securities Exchange Act of 1934, as
               amended ("a Private Company"), or of a majority of the
               outstanding voting securities of the Company to a Private
               Company, in a single transaction or in a series of related
               transactions which occurs after March 2, 2002."

         2.    Definitions.
               -----------

               2.1   Definition of Mandatory Convertible Debt. A new definition
is hereby added to the Note as Section 1.7 to read as follows: " `Mandatory
Convertible Debt" shall mean all of the principal amount of this Note and all of
the accrued but unpaid interest on this Note, as reduced by (i) any prepayments
made by the Company as permitted in Section 4 hereof and (ii) any conversion
pursuant to Section 2.2 of this Note."

               2.2   Definition of Optional Convertible Debt. A new definition
is hereby added to the Note as Section 1.8 to read as follows: " `Optional
Convertible Debt" shall mean $712,500 of the principal amount of this Note and
all of the accrued but unpaid interest on such principal, as reduced by any
prepayments made by the Company as permitted in Section 4 hereof."

               2.3   Definition of Conversion Stock. Section 1.2 of the Note is
hereby amended to read as follows: " `Conversion Stock' shall mean shares of
Common Stock of the Company, with respect to conversion of the Optional
Convertible Debt, and shall mean Common Stock of the Company of the same class
of common stock that is registered by the Company pursuant to an Initial Public
Offering, with respect to conversion of the Mandatory Convertible Debt. With
respect to Optional Convertible Debt, if the outstanding Common Stock of the
Company shall hereafter be changed through a reorganization or recapitalization
into shares of a different series or class of the Company's capital stock, the
Conversion Stock shall thereafter mean the shares into which the Common Stock
was changed."

               2.4   Definition of Conversion Price. Section 1.3 of the Note is
hereby amended to read as follows: " The `Conversion Price' for Optional
Convertible Debt shall mean $8.01 per share of Conversion Stock, as
appropriately adjusted to reflect the effect of stock splits and combinations,
stock dividends, recapitalizations and reorganizations of or on the Conversion
Stock after the date hereof. For Mandatory Convertible Debt, the `Conversion
Price' shall mean the price per share that is the exact middle of the price
range stated in the Company's final amended registration statement on Form S-1,
Form SB-1, Form SB-2 or a similar successor form pertaining to an Initial Public
Offering that closes on before the Maturity Date. No conversion shall occur and
there is therefore no Conversion Price with respect to an Initial Public
Offering that closes after the Maturity Date."

         3.    Conversion. Section 2 of the Note is hereby amended to read as
follows:

                     "2.1   Mandatory Conversion. This Note and all of the
               outstanding Mandatory Convertible Debt shall be converted into
               Conversion Stock at the Conversion Price immediately prior to the
               first


                                        2

<PAGE>

               closing of an Initial Public Offering before the Maturity Date.
               For informational purposes, the Company shall provide the
               Noteholder with written notice (at the most recent address for
               the Noteholder provided to the Company by the Noteholder in
               writing) (i) within seven days after it files with the Securities
               and Exchange Commission any registration statement on Form S-1,
               Form SB-1 or Form SB-2 (or any similar or successor form) for an
               Initial Public Offering, and (ii) reasonably promptly following
               the closing of an Initial Public Offering. Conversion as
               described in this Section 2.1 shall occur only upon the closing
               of an Initial Public Offering, provided that (i) upon the closing
               of an Initial Public Offering, the conversion shall be deemed to
               have occurred immediately prior to the first closing of such
               Initial Public Offering, and (ii) as a condition precedent or
               condition subsequent to conversion (the election between which
               type of condition shall be the Company's sole election in the
               Company's sole discretion), the Noteholder must surrender this
               Note for conversion at the principal office of the Company.
               Incident to any conversion, the Conversion Stock will have those
               rights and privileges, and be subject to those restrictions, of
               the shares of Common Stock as set forth in the Company's
               Certificate of Incorporation, and the Noteholder will receive the
               rights and be subject to the obligations applicable to the
               purchasers of Common Stock, provided that the sale restriction
               specified in Section 2.6 below shall apply to the Conversion
               Stock. This Note shall not be convertible pursuant to this
               Section 2.1 and shall not be converted into Conversion Stock
               under this Section 2.1 if there is not an Initial Public Offering
               on or before the Maturity Date.

                     2.2    Optional Conversion.
                            -------------------

                            2.2.1   If not previously converted pursuant to
               Section 2.1 above, all of the outstanding Optional Convertible
               Debt may be converted, at any time prior to the Maturity Date,
               into Conversion Stock at the Conversion Price in the sole
               discretion of the Company. To elect to convert the Optional
               Convertible Debt, the Company shall send written notice of its
               election to the Noteholder prior to the Maturity Date. Noteholder
               will thereafter deliver the original Note to the Company at the
               Company's principal office for reissuance to reflect the
               conversion of the Optional Convertible Debt. Incident to any
               conversion, the Conversion Stock will have those rights and
               privileges, and be subject to those restrictions, of the shares
               of Conversion Stock as set forth in the Company's Certificate of
               Incorporation, and the Noteholder will receive the rights and be
               subject to the obligations applicable to the purchasers of
               Conversion Stock, provided that the sale restriction specified in
               Section 2.6 below shall apply to the Conversion Stock.

                            2.2.2   In the event of any conversion pursuant to
               this Section 2.2 prior to March 2, 2004, the Company shall pay to
               Noteholder,

                                        3

<PAGE>

               in cash, an amount equal to the lesser of (a) the United States
               state and federal capital gains tax imposed on Noteholder as a
               result of the receipt of such Conversion Stock or (b) an amount
               equal to the outstanding principal and accrued but unpaid
               interest then represented by this Note (the "Tax Payment"). The
               amount paid by the Company shall be offset first against any
               accrued but unpaid interest due hereunder and then against the
               outstanding principal amount of this Note. Upon conversion of
               this Note pursuant to this Section 2.2 and calculation of
               Noteholder's capital gains tax therefor, Noteholder will give the
               Company at least 30 days prior written notice thereof to permit
               the Company to verify the capital gains calculation made by
               Noteholder and will deliver such information to the Company as
               may be necessary to conduct such verification. The Tax Payment
               shall be made by the Company after the 30-day verification period
               but need not be paid earlier than 10 days prior to the time
               Noteholder's capital gains tax must be paid in connection with
               conversion of this Note as provided in this Section 2.2 above.

                            2.2.3   If the Company fails to deliver the written
               notice of conversion provided for in Section 2.2.1 prior to the
               Maturity Date, the conversion right of the Company that is set
               forth in this Section 2.2 shall terminate on the Maturity Date.

                     2.3    No Fractional Shares. No fractional shares will be
               issued on conversion of this Note. If on any conversion of this
               Note a fraction of a share results, the Company will pay the cash
               value of that fractional share, calculated on the basis of the
               applicable Conversion Price.

                     2.4    Reservation of Stock. Prior to any conversion of
               this Note pursuant to this Section 2 above, the Company will take
               such corporate action and obtain such government consents and
               approvals as may, in the reasonable opinion of its counsel, be
               necessary to authorize the issuance of a sufficient number of
               shares of Conversion Stock into which this Note is to convert.

                     2.5    Fully Paid Shares; Certificates. All shares of
               Conversion Stock issued upon the conversion of this Note shall be
               validly issued, fully paid and non-assessable. The certificates
               representing the shares of Conversion Stock issued upon
               conversion hereof shall be delivered to the holder against
               surrender of this Note. The holder, by accepting this Note,
               undertakes and agrees to accept such shares of Conversion Stock
               in full satisfaction of the Optional Convertible Debt or of the
               Mandatory Convertible Debt, as the case may be, that is
               outstanding as of the effective date of conversion in accordance
               with the terms of this Note. Anything to the contrary in this
               Note notwithstanding, the Company's obligation to issue shares of
               Conversion Stock to any holder of this Note is expressly
               conditioned upon compliance of such issuance with applicable

                                        4

<PAGE>

               federal and state securities laws without registration or other
               qualification thereunder.

                     2.6    Restriction on Sale. Upon and following any
               conversion pursuant to this Section 2, no holder of any
               Conversion Stock shall effect any sale or distribution of any of
               the Conversion Stock (which shall include any and all voting
               securities received by such holder as or in connection with a
               stock dividend, stock split or other recapitalization or similar
               distribution on or in respect of the Conversion Stock) or any of
               the Company's other equity securities, or of any securities
               convertible into or exchangeable for such securities, during the
               period beginning on the closing of the Initial Public Offering
               and ending 180 days after such closing. The certificate(s)
               representing the shares of Conversion Stock issued upon the
               conversion of this Note shall be legended to reflect such
               restriction on sale.

                     2.7    No Rights or Liabilities as Shareholder. This Note
               does not by itself entitle the Noteholder to any voting rights or
               other rights as a shareholder of the Company. In the absence of
               conversion of this Note, no provisions of this Note, and no
               enumeration herein of the rights or privileges of the holder
               shall cause such holder to be a shareholder of the Company for
               any purpose by virtue hereof.

                     2.8    No Other Conversion. The conversion provisions set
               forth in this Section 2 constitute the sole methods by which this
               Note will convert."

         4.    Effect of Prepayments. There is hereby added an additional
sentence at the end of Section 4 of the Note to read as follows: "In the event
of any partial prepayment of the Note, the amount prepaid shall be credited
towards the Optional Convertible Debt and/or any portion of the Mandatory
Convertible Debt that does not constitute Optional Conversion Debt, as specified
at the time of such prepayment by the Company, in its sole discretion, until the
Note is repaid in full."

         5.    Effect of Amendment. This Amendment will be effective as of the
date first set forth above, upon execution of this Amendment by the Company and
Payee. This Amendment may be executed in any number of counterparts, each of
which shall be deemed an original and all of which, taken together, will
constitute one and the same Amendment. Except as expressly provided above, the
terms and conditions of the Note remain in full force and effect, unmodified, as
of the date hereof. None of the rights of Payee under the Note or this Amendment
shall be terminated, waived, or otherwise adversely affected by any termination
by Payee or the Company of Payee's employment with the Company.

                                        5

<PAGE>

         In Witness Whereof, Payee and the Company have executed this Amendment
to Convertible Subordinated Promissory Note, in the case of the Company by a
person duly authorized to do so.

THE COMPANY: DOVEBID, INC.               PAYEE: RICHARD E. SCHMITT



By: /s/ Anthony Capobianco                       /s/ Richard E. Schmitt
   --------------------------------      ---------------------------------------
                                                (Signature of Payee)
Title: VP and General Counsel
      -----------------------------

                                        6